Ap Stats Review, AP Statistics - Final Exam Study Guide (V.2)

) A scientist recorded the duration of the eruption of the Old Faithful geyser in Yellowstone National Park that occurred during a one-month time period. The histogram below shows the distribution of the duration, in seconds, of the eruptions.

2) Which of the variables you collect are continuous data?

3) What are the categorical variables in your survey?

4) Given that the median is 270 and the interquartile range is 20, which of the following statements is true?

5) In population H, what is the height, to the nearest tenth of an inch, of the 70th percentile?

6) In population H, what is the z-score, to the nearest tenth, associated with the height 65 inches?

7) To the nearest whole number, what percentile is associated with z = -0.68?

8) Why is the IQR considered to be a resistant statistic?

9) Events D and E are independent, with P(D) = 0.6 and P(D and E) = 0.18. Which of the following is true?

10) An airline recorded the number of on-time arrivals for a sample of 100 flights each day. The boxplot below summarizes the records data for one year.

11) Which of the following can outliers affect significantly?

12) Given these parallel boxplots, which of the following is incorrect?

13) Which of the following is true about the areas described under the normal curve?

14) In which of the following histograms is the mean less than the median?

15) A random sample of golf scores gives the following summary statistics: n=20, x ?=84.5, S_x=11.5, minX=68,Q_1=78,Med=86,Q_3=91,maxX=112. What can be said about the number of outliers?

19) A tropical storm is classified as major if it has sustained winds greater than 110 miles per hour. Based on data from the past two decades, a meteorologist estimated the following percentages about future storms.

20) To which of the histograms below can the boxplot correspond?

22) Research indicates that the standard deviation of typical body temperate is 0.4 degrees Celsius (C). Which of the following represents the standard deviation of typical human body temperature in degrees Fahrenheit (F), where F=9/5 C+32?

24) An AP Statistics teacher grades using z-scores. On the second major exam of the marking period, a student receives a grade with a z-score of -1.3. What is the correct interpretation of this grade?

25) The number of adults living in homes on a randomly selected city block is described by the following probability distribution.

26) Given two independent random variables, X with mean 12.3 and standard deviation 0.5 and Y with mean 9.1 and standard deviation 0.3, which of the following is a true statement?

28) Suppose the scores on an exam have a mean of 75 with a standard deviation of 8. If one student has a test result with a z-score of -1.5, and a second student has a test result with a z-score of 2.0, how many points higher was the second student's result than that of the first?

29) A national achievement test is administered annually to 3rd graders. The test has a mean score of 100 and a standard deviation of 15. If Jane's z-score is 1.20, what was her score on the test?

30) An advantage to using surveys as opposed to experiments is that

31) Suppose X and Y are independent random variables. The variance of X is equal to 16; and the variance of Y is equal to 9. Let Z = X - Y.

32) A company wishes to survey what people think about a new product it plans to market. They decide to randomly sample from their customer database as this includes phone numbers and addresses. This procedure is an example of which type of sampling?

33) The back-to-back stemplot on the right shows the number of books read in a year by a random sample of college and high school students. Which of the following statements are true?

34) A bank wishes to survey its customers. The decision is made to randomly pick ten customers who just have checking accounts, ten customers who just have savings accounts, and ten customers who have both checking and savings accounts. This procedure is an example of which type of sampling?

35) Two antidepressants are to be compared in the treatment of elderly patients in a nursing home. Each patient has his or her own room, some with spectacular views of the ocean. The experimental design is to create homogeneous blocks with respect to window view. How should randomization be used for a randomized block design?

36) Which of the following statements is incorrect?

37) A critical difference between experiments and observational studies is

38) Measurements of water quality were taken from a river downstream from an abandoned chemical dumpsite. Concentrations of a certain chemical were obtained from 9 measurements taken at the surface of the water, 9 measurements taken at mid-depth of the water, and 9 measurements taken at the bottom of the water. What type of study was conducted, and what is the response variable of the study?

39) A materials engineer wishes to compare the durability of two different types of paving material. She has 40 different one-mile stretches of interstate highway that she's been authorized to repave for this study. She decides to carry out a matched pairs experiment. Which of the following is the best way for her to carry out the randomization for this study?

43) If P(A)=.25 and P(B)=.34, what is P(A?B) if A and B are independent?

44) An auto analyst is conducting a satisfaction survey, sampling from a list of 10,000 new car buyers. The list includes 2,500 Ford buyers, 2,500 GM buyers, 2,500 Honda buyers, and 2,500 Toyota buyers. The analyst selects a sample of 400 car buyers, by randomly sampling 100 buyers of each brand.

45) People with type O-negative blood are universal donors. That is, any patient can receive a transfusion of O-negative blood. Only 7.2% of the American population has O-negative blood. If 10 people appear at random to give blood, what is the probability that at least 1 of them is a universal donor?

46) Which of the following are true?

49) Staff members of a high school newspaper want to obtain an estimate of the average number of years teachers in the state have been teaching. At an educational conference attended by many teachers in the state, the staff members randomly selected 50 conference attendees and asked the attendees how long they have been teaching. Which of the following describes the sample and the population to which it would be most reasonable for the staff members to generalize the results?

50) Suppose P(X)=.25 and P(Y)=.40. If P(X?Y)=.20, what is P(Y|X)?

51) It is estimated that 20 percent of all drivers do not signal when changing lanes. In a random sample of four drivers, what is probability that at least one doesn't signal when changing lanes?

52) A study was conducted to evaluate the impact of taking a nutritional supplement on a person's reaction time. One hundred volunteers were placed into one of three groups according to their athletic ability: low, moderate, or high. Participants in each group were randomly assigned to take either the nutritional supplement or a placebo for six weeks. At the end of the six weeks, participants were given a coordination task. The reaction time in completing the task was recorded for each participant. The study compared the reaction times between those taking the supplement and those taking the placebo within each athletic ability level. Which of the following is the best description of the study?

53) The average noise level in a bar is 36 decibels with a standard deviation of 5 decibels. Assuming a normal distribution, what is the probability the noise level is between 30 and 40 decibels?

55) The number of tickets purchased by a customer for the Ice Hogs game at BMO Harris Bank center can be considered a random variable. The table below show the relative frequency distribution for the number of tickets purchased by a customer.

56) Molly earned a score of 940 on a national achievement test. The mean test score was 850 with a standard deviation of 100. What proportion of students had a higher score than Molly? (Assume that test scores are normally distributed.)

57) Give, in millimeters, a minimum and maximum thickness that includes 68% of the population of bolts.

58) Give, in millimeters, a minimum and a maximum thickness that will include 95% of the population of bolts.

59) The SAT math scores for applicants to a particular engineering school are normally distributed with a mean of 680 and a standard deviation of 35. Suppose that only applicants with scores above 700 are considered for admission. What percentage of the applicants considered have scores below 750?

60) Given two events, E and F, such that P(E)=.340,P(F)= .450, and P(E?F)=.637, then the two events are:

61) The number of hybrid cars a dealer sells weekly has the following probability distribution:

62) Rainwater was collected in water collectors at 30 different sites near an industrial complex and the amount of acidity (pH level) was measured. The data ranged from pH 2.6 to pH 6.3. The following stemplot of the data was constructed

63) Ms. Fisher wants to compare the effect of a new fertilizer on that of three older fertilizers - X, Y, and Z - on the growth of vegetables typically grown in small gardens. Two hundred green bean seedlings were individually planted in identical pots and randomly assigned to one of four groups of 50 each. Seedlings in one group were given the new fertilizer, and the three remaining groups of seedlings were given fertilizers X, Y, or Z, respectively. At the end of four weeks, all seedlings were dried and weighed. Ms. Fisher found that the mean weight of the seedlings in the group given the new fertilizer were significantly greater than the mean weights of seedlings in the other three groups. The scientists concluded that the new fertilizer was more effective than the other fertilizers for all vegetables. Why is Ms. Fisher's conclusion not appropriate?

64) Using the empirical rule, you can assume that what percent of the normal distribution is outside two standard deviations of the mean in both directions?

66) A set of data has a mean that is much larger than the median. Which of the following statements is most consistent with this information?

67) If the standard deviation of a set is 0, you can conclude

68) As part of a study on the relationship between the use of tanning booths and the occurrence of skin cancer, researchers reviewed the medical records of 1,436 people. The table below summarizes tanning booth use for people in the study who did and did not have skin cancer.

69) A business evaluates a proposed venture as follows. It stands to make a profit of $10,000 with probability 3/20, to make a profit of $5,000 with probability 9/20, to break even with probability 5/20, and to lose $5,000 with probability 3/20. The expected profit in dollars is

70) Control groups are used in experiments in order to ...

71) A sample of production records for an automobile manufacturer shows the following figures for production per shift:

72) Halle takes three standardized tests. She scores 600 on all three. Using standardized scores (z-scores), rank her performance on the three tests from best to worst if the means and standard deviations of the tests are as follows:

73) A researcher interested in the age at which women have their first child surveyed a simple random sample of 250 women who have one child and found an approximately normal distribution with a mean age of 27.3 and a standard deviation of 5.4. According to the 68-95-99.7 rule, approximately 95% of women had their first child between the ages of

74) The scores on a real estate licensing examination given in a particular state are normally distributed with a standard deviation of 70. What is the mean test score if 25% of the applicants scored above 475?

75) The mean of a data set is 40 pounds and the standard deviation is 8 pounds. What value of an observation corresponds to a z-score of -1.25?

77) Assume X and Y are events in the same sample space. If P(X) = 0.30 and P(Y) = 0.75 then which of the following inequalities must be true?

78) A company determines the mean and standard deviation of the number of sick days taken by its employees in one year. Which of the following is the best description of the standard deviation?

81) A researcher is testing a company's new stain remover. He has contracted with 40 families who have agreed to test the product. He randomly assigns 20 families to the group that will use the new stain remover and 20 to the group that will use the company's current product. The most important reason for this random assignment is that

82) 100 volunteers who suffer from anxiety take part in a study. 50 are selected at random and assigned to receive a new drug that is thought to be extremely effective in reducing anxiety. The other 50 are given an existing anti-anxiety drug. A doctor evaluates anxiety levels after two months of treatment to determine if there has been a larger reduction in the anxiety levels of those who take the new drug. This would be double blind if

83) A marketing survey complied data on the number of cars in households. If X = the number of cars in a randomly selected household, and we omit the rare cases of more than 5 cars, the X has the following probability distribution:

84) Using the problem above, what is the expected value of the number of cars in a randomly selected household?

85) In the town of Lakeville, the number of cell phones in a household is a random variable W with the following probability distribution:

88) The probability that a child will have a problem with alcohol is 0.75 if at least one of the parents is an alcoholic and 0.05 if neither parent is an alcoholic. In a recent study of a large number of children, 5% of the children involved had at least one parent who is an alcoholic. If a child in this study has an alcohol-related problem, what is the probability that at least one of the parents of the child is an alcoholic?

89) The weights of newborn baby boys have an approximately normal distribution with a mean of 8.0 pounds and a standard deviation of 1.5 pounds. A doctor tells a mother that her newborn baby boy has a weight at the 25th percentile. Which of the following is closest to this baby's weight?

90) The dotplot below displays the daily high temperature, in degrees Fahrenheit, for a city in the southeastern United States during the 28 days in the month of February 2014.

92) Let the random variable X represent the profit made on a randomly selected day by a certain store. Assume that X is Normal with mean $360 and standard deviation $50. What is P(X>$400)?

93) Which of the following random variables has a distribution which most closely resembles a normal distribution?

97) Which of the following statements is true for two events, each with probability greater than 0?

98) The SC Electric Company has bid on two electrical wiring jobs. The owner of the company believes that

103) Suppose the probability that a softball player gets a hit in any single at-bat is .300. Assuming that her chance of getting a hit on a particular time at bat is independent of her other at bats, what is the probability that she will not get a hit until her fourth time at bat in a game?

108) A large bakery has many different products for sale. Suppose that 70% of all customers of the bakery order donuts, 50% order cinnamon rolls, and 40% order both. If a customer is randomly selected, what is the probability that they ordered either donuts or cinnamon rolls but not both?

1. The histogram summarizes the responses of 100 people when asked,"What was the price of the last meal you purchased?" Based on the histogram, which of the following could be the interquartile range of the prices? A) $40 B) $21 C) $10 D) $5 E) $3

2. Suppose a certain scale is not calibrated correctly, and as a result, the mass of any object is displayed as 0.75 kilogram less that its actual mass. What is the correlation between the actual masses of a set of objects and the respective masses of the same set of objects displaced by the scale? A) -1 B) -0.75 C) 0 D) 0.75 E) 1

3. A veterinarian collected data on the weights of 1,000 cats and dogs treated at a veterinary clinic. The weight of each animal was classified as either healthy, underweight, or overweight. The data are summarized in the table. Based on the data in the table, which of the following is the appropriate type of graph to visually show whether a relationship exists between the type of animal and the weight classification. A) Back-to-back stemplots B) Scatterplot C) Side-by-side boxplots D) Segmented bar chart E) Dotplot

5. The normal curve shown represents the sampling distribution of a sample mean for a sample size n=25, selected at random from a population with a standard deviation Ox. Which of the following is the best estimate of the standard deviation of the population, Ox? A) 3 B) 6 C) 15 D) 30 E) 75

6. Two random samples, A and B, were selected from the same population to estimate the population mean. For each sample, the mean, standard deviation, and margin of error for a 95 percent confidence interval for the population mean are show in the table. Which of the following could explain why the margin of error of sample A is greater than the margin of error of Sample B? A) The sample size of A is greater than the sample size of B. B) The sample size of A is less than the sample size of B. C) The sample size of A is equal to the sample size of B. D) The mean of sample A is greater than the mean of sample B. E) The standard deviation of sample A is less than the standard deviation of sample B.

7. Nyasha's financial literacy project involved comparing the annual sales of companies in Canada and companies in the US that produce software. Using the ratio of 1 CAD to 0.75 USD, she converted all annual sales from the Canadian companies into United States dollars. For which of the following will the value of statistics for the annual sales in Canadian dollars be equal to the value of the corresponding statistic in US dollars? A) The median annual sales B) The standard deviation of annual sales C) The standardized score of the minimum annual sales D) The mean annual saless E) The interquartile range of the annual sales

8. The manager of a restaurant tracks the types of dinners that customers order from the menu to ensure that the correct amount of food is ordered from the supplier each week. Data from customer orders last year suggest the following weekly distribution. The manager believes that there might be a change in the distribution from last year to this year. A random sample of 200 orders was taken from all customer orders placed last week. The following table shows the results of the sample. Assume each order is independent. For which type of dinner is the value of its contribution to the appropriate test statistic the greatest? A) Beef B) Chicken C) Fish D) Pork E) Vegetarian

A company that makes fleece clothing uses fleece produced from two farms, Northern Farm and Western Farm. Let the random variable X represent the weight of fleece produced by a sheep from Northern Farm. The distribution of X has a mean 14.1 pounds and a standard deviation 1.3 pounds. Let the random variable Y represent the weight of fleece produced by a sheep from Western Farm. The distribution of Y has a mean 6.7 pounds and a standard deviation of 0.5 pounds. Assume X and Y are independent. Let W equal the total weight of fleece from 10 randomly selected sheep from Northern Farm and 15 randomly selected sheep from Western Farm. Which of the following is the standard deviation, in pounds, of W? A) 1.3+0.5 B) sqrt(1.3^2+0.5^2) C) sqrt(10(1.3)^2+15(0.5)^2) D) sqrt(10^2(1.3)^2+15^2(0.5)^2) E) sqrt((1.3)^2/10 + (0.5)^2/15

10. According to a report for veterinarians in the United States, 36.5 percent of households in the United States own dogs and 30.4 percent of households in the United States own cats. If one household in the United States is selected at random, what is the probability that the selected household will own a dog or a cat? A) 0.111 B) 0.331 C) 0.558 D) 0.669 E) Not enough information is given to determine the probability.

11. A sociologist collected data from a sample of people on their highest level of education and the number of times they visited any fast food restaurant during the previous week. The data are summarized in the boxplots. Based on the boxplots, which of the following statements must be true? A) The number of people surveyed at the more than 4 year college level is greater than the number of people surveyed at the high school level. B) The proportion of people surveyed from the first quartile to the third quartile at the 4 year college level is less than the respective proportion at the community college level. C) The interquartile range (IQR) for the number of visits at the more than 4 year college level is less than the IQR for the number of visits at the community college level. D) The maximum number of visits at the community college level is greater than the maximum number of visits at the high school level. E) The median number of visits at the 4 year college level is greater than the median number of visits at the high school level.

12. For a recent season in college football, the total number of rushing yards for that season is recorded for each running back. The mean number of rushing yards for the running backs that season is 790 yards. One running back had 1,637 rushing yards for the season, which is 2.42 standard deviations above the mean number of rushing yards. What is the standard deviation of the number of rushing yards for the running backs that season? A) 250 yards B) 300 yards C) 350 yards D) 400 yards E) 450 yards

13. First year students enrolled at a college were asked whether they play video games. The responses, classified by whether the students were enrolled in the school of sciences or the school of arts are shown in the table. Of all the students enrolled in the school of arts who responded, approximately what proportion responded that they play video games. A) 0.242 B) 0.401 C) 0.438 D) 0.554 E) 0.605

14. A pharmaceutical company manufactures medicine to reduce pain caused by migraine headaches. The company is investigating whether a new medicine is more effective in reducing pain than the current medication. A random sample of 500 participants who experience migraines was selected, and the participants were randomly assigned to one of the two groups of equal size. The first group received the current medicine and the second group received the second medicine. When a participant got a migraine, they were instructed to take the medicine and, 15 minutes after taking the medicine, to rate the pain relief on a scale from 1 to 10, 1=no relief, 10=complete relief. At the end of the 6 months, the average pain relief for each participant was calculated. Which of the following is a description of the study. A) An experiment using a completely randomized design B) An experiment using a matched-pairs design C) An observational study using a simple random sample D) An observational study using a cluster sample. E) An observational study using a stratified sample.

15. A marketing firm obtained random samples of 20 people in five regions of the country to investigate the level of interest in a new product. People in the same were asked to rate their level of interest on a scale from 1 to 10, with 1 being the least amount of interest and 10 being the greatest. The histograms show the results for each region. The graph for which region displays data for level of interest with the least standard deviation?

16. The transportation department of a large city wants to estimate the proportion of residents who would use a system of aerial gondolas to commute to work. The gondolas would be part of the city's effort to relieve traffic congestion. The department asked a random sample of residents whether they would use the gondolas. The residents could respond with yes, no, or maybe. Which of the following is the best description of the method for data collection used by the department? (A) A census (B) A sample survey (C) An experiment with a completely randomized design (D) An experiment with a randomized block design (E) An experiment with a matched-pairs design

17. To obtain certification for a certain occupation, candidates take a proficiency exam..The exam consists of two sections, and neither section should be more difficult than the other. To investigate whether one section of the exam was more difficult than the other, a random sample of 50 candidates was selected. The candidates took the exam and their scores on each section were recorded. The table shows the summary statistics. Which of the following is the test statistic for the appropriate test to determine if there is a significant mean difference between the percent correct on the two sections (first minus second) for all candidates similar to those in the investigation?

18. New employees at a large corporation go through a training program during their first week of employment. The new employees take a written assessment at the completion of the program to determine how well prepared they are for their jobs. A score greater than the mean indicates a well-prepared employee. Assume the following distributions of new employee scores have the same mean score, the same maximum score, and the same minimum score. Which distribution has a shape that is most likely to represent the greatest percent of well-prepared employees? (A) The distribution of scores is skewed to the right. (B) The distribution of scores is skewed to the left. (C) The distribution of scores is bimodal and symmetric. (D) The distribution of scores is uniform. (E) The distribution of scores is approximately normal.

19. Based on his past record, Luke, an archer for a college archery team, has a probability of 0.90 of hitting the inner ring of the target with a shot of the arrow. Assume that in one practice Luke will attempt 5 shots of the arrow and that each shot is independent from the others. Let the random variable X represent the number of times he hits the inner ring of the target in 5 attempts. The probability distribution of X is given in the table. What is the probability that the number of times Luke will hit the inner ring of the target out of the 5 attempts is less than the mean of X ? (A) 0.40951 (B) 0.50000 (C) 0.59049 (D) 0.91854 (E) 0.99144

20. A medical center conducted a study to investigate cholesterol levels in people who have had heart attacks. A random sample of 16 people was obtained from the names of all patients of the medical center who had a heart attack in the previous year. Of the people in the sample, the mean cholesterol level was 264.70 milligrams per deciliter (mg/dL) with standard deviation 42.12 mg/dL. Assuming all conditions for inference were met, which of the following is a 90 percent confidence interval for the mean cholesterol level, in mg/dL, of all patients of the medical center who had a heart attack in the previous year? (A) (242.26, 287.14) (B) (244.06, 285.34) (C) (246.24, 283.16) (D) (247.38, 282.02) (E) (260.09, 269.31)

21. For a school fund-raiser, 600 raffle tickets were sold by students at the school, of which 88 were sold by one student, Audrey. Of the 600 tickets sold, 30 were randomly selected to receive prizes, and 7 of the 30 tickets selected were tickets sold by Audrey. To investigate how likely it was by chance alone that at least 7 of the 30 selected tickets could have been sold by Audrey, students in a statistics class ran a simulation. One trial of the simulation is described by the following steps. Step 1: From 600 chips, assign 88 red and the rest blue. Step 2: Select 30 chips at random without replacement. Step 3: Record the number of red chips in the selection of 30. Based on the results of the simulation, is there convincing statistical evidence at the significance level of 0.05 that the event of Audrey selling at least 7 of the 30 selected tickets is unlikely to have occurred by chance alone? (A) Yes, because the distribution of the trials in the simulation is skewed to the right. (B) Yes, because the number in the histogram with the greatest frequency is 4, not 7. (C) Yes, because 7 appears in the right tail of the distribution, indicating that it is more than 2 standard deviations away from the mean. (D) No, because the simulation suggests that it is likely that Audrey could sell anywhere from 0 to 11 of the selected tickets. (E) No, because the simulation suggests that Audrey selling at least 7 of 30 selected tickets would occur about 13.8% of the time.

22. As part of a study on facility needs, the administrators of a university wanted to estimate the percent of students who use the exercise facilities on a regular basis. From the 34,000 students who attend the university, a random sample of 370 male students and 400 female students was selected. Of the 770 students selected, 493 students indicated that they use the exercise facilities on a regular basis. What are the population and the sample of the study? (A) The population is the 770 students who were selected, and the sample is the 493 students who indicated that they use the exercise facilities on a regular basis. (B) The population is the 770 students who were selected, and the sample is whether each student in the survey uses the exercise facility on a regular basis. (C) The population is the 34,000 students who attend the university, and the sample is whether each student in the survey is male or female. (D) The population is the 34,000 students who attend the university, and the sample is the 770 students who were selected. (E) The population is the 34,000 students who attend the university, and the sample is the 493 students who indicated that they use the exercise facilities on a regular basis.

23. A study will be conducted to examine a new medicine intended to reduce high blood pressure in adult men who have high blood pressure. As part of the study, a random sample of 40 men with high blood pressure will have their blood pressure measured, and then they will take the new medicine every day for one month. At the end of the month, their blood pressure will be measured again. Of the following, which is the best procedure to investigate whether there will be convincing statistical evidence of a change, on average, in blood pressure for men with high blood pressure who take the new medicine? (A) A one-sample z-test for a proportion (B) A two-sample z-test for a difference between proportions (C) A two-sample -test for the difference between two means (D) A matched-pairs t-test for a mean difference (E) A chi-square test of independence

24. A roadrunner is a desert bird that tends to run instead of fly. While running, the roadrunner uses its tail as a balance. A sample of 10 roadrunners was taken, and the birds' total length, in centimeters (cm), and tail length, in cm, were recorded. The output shown in the table is from a least-squares regression to predict tail length given total length. Suppose a roadrunner has a total length of 59.0 cm and tail length of 31.1 cm. Based on the residual, does the regression model overestimate or underestimate the tail length of the roadrunner? (A) Underestimate, because the residual is positive. (B) Underestimate, because the residual is negative. (C) Overestimate, because the residual is positive. (D) Overestimate, because the residual is negative. (E) Neither, because the residual is 0.

25. The distribution of assembly times required to assemble a certain smartphone is approximately normal with mean 4.6 minutes and standard deviation 0.6 minute. Of the following, which is closest to the percentage of assembly times between 4 minutes and 5 minutes? (A) 34% (B) 41% (C) 59% (D) 68% (E) 95%

26. A company produces millions of 1-pound packages of bacon every week. Company specifications allow for no more than 3 percent of the 1-pound packages to be underweight. To investigate compliance with the specifications, the company's quality control manager selected a random sample of 1,000 packages produced in one week and found 40 packages, or 4 percent, to be underweight. Assuming all conditions for inference are met, do the data provide convincing statistical evidence at the significance level of a@ = 0.05 that more than 3 percent of all the packages produced in one week are underweight? (A) Yes, because the sample estimate of 0.04 is greater than the company specification of 0.03. (B) Yes, because the p-value of 0.032 is less than the significance level of 0.05. (C) Yes, because the p-value of 0.064 is greater than the significance level of 0.05. (D) No, because the p-value of 0.032 is less than the significance level of 0.05. (E) No, because the p-value of 0.064 is greater than the significance level of 0.05.

27. The histograms show the results of three simulations of a sampling distribution of a sample mean. For each simulation, 1,500 samples of size n were selected from the same population and the sample mean was recorded. The value of n was different for each of the three simulations. Which of the following is the correct ordering of the graphs from least value of n to greatest value of n? (A) A, C, B (B) B, A, C (C) B,C, A (D) C, A, B (E) C,B,A

28. Researchers conducted a study to investigate the effects of soft drink consumption on fat stored in muscle tissue. From a sample of 80 adult volunteers, 40 were randomly assigned to consume one liter of a soft drink each day. The remaining 40 were asked to drink one liter of water each day and not to consume any soft drinks. At the end of six months, the amount of fat stored in each person's muscle tissue was recorded. The people in the group who drank the soft drink had, on average, a higher percentage of fat stored in the tissue than the people who drank only water. Which of the following is the most appropriate conclusion? (A) There is evidence that consuming soft drinks causes more fat storage in muscle tissue than drinking only water, and the conclusion can be generalized to all adults. (B) There is evidence that consuming soft drinks causes more fat storage in muscle tissue than drinking only water, and the conclusion can be generalized to all people who consume soft drinks. (C) There is evidence that consuming soft drinks causes more fat storage in muscle tissue than drinking only water, and the conclusion can be generalized to adults similar to those in the study. (D) Although cause-and-effect cannot be established, there is an association between consuming soft drinks and fat storage in muscle tissue for the population of all adults. (E) Although cause-and-effect cannot be established, there is an association between consuming soft drinks and fat storage in muscle tissue for the population of all adults who consume soft drinks.

29. A random sample of 1,018 city residents were asked to rate their level of support for a proposal being considered by the city council. The table shows the responses by level of support. Based on the responses, which of the following is a 95 percent confidence interval for the proportion of all city residents who would respond very supportive or somewhat supportive of the proposal? (A) 0.33 +- 0.029 (B) 0.38 +- 0.030 (C) 0.71 +- 0.058 (D) 0.71 +- 0.031 (E) 0.71 +- 0.028

30. A manufacturer of cell phone batteries claims that the average number of recharge cycles for its batteries is 400. A consumer group will obtain a random sample of 100 of the manufacturer's batteries and will calculate the mean number of recharge cycles. Which of the following statements is justified by the central limit theorem? (A) The distribution of the number of recharge cycles for the sample is approximately normal because the population mean of 400 is greater than 30. (B) The distribution of the number of recharge cycles for the sample is approximately normal because the sample size of 100 is greater than 30. (C) The distribution of the number of recharge cycles for the population is approximately normal because the sample size of 100 is greater than 30. (D) The distribution of the sample means of the number of recharge cycles is approximately normal because the sample size of 100 is greater than 30. (E) The distribution of the sample means of the number of recharge cycles is approximately normal because the population mean of 400 is greater than 30.

31. A news organization conducted a survey about preferred methods for obtaining the news. A random sample of 1,605 adults living in a certain state was selected, and 16.2 percent of the adults in the sample reported that television was their preferred method. Which of the following is an appropriate margin of error for a 90 percent confidence interval to estimate the population proportion of all adults living in the state who would report that television is their preferred method for obtaining the news?

32. A fitness center offers a one-month program designed to reduce body fat through exercise. The table shows the body fat percentage before and after completing the program for 10 randomly selected participants. The director of the program wants to investigate whether knowing the body fat percentage before beginning the program can help to predict body fat percentage for someone who completes the program. Which of the following procedures is the most appropriate for such an investigation? (A) A matched-pairs t-test for a mean difference (B) A two-sample t-test for a difference between means (C) A two-sample z-test for a difference between proportions (D) A chi-square test of association (E) A linear regression t-test for slope

33. A recent survey estimated that 19 percent of all people living in a certain region regularly use sunscreen when going outdoors. The margin of error for the estimate was 1 percentage point. Based on the estimate and the margin of error, which of the following is an appropriate conclusion? (A) Approximately 1% of all the people living in the region were surveyed. (B) Between 18% and 20% of all the people living in the region were surveyed. (C) All possible samples of the same size will result in between 18% and 20% of those surveyed indicating they regularly use sunscreen. (D) The probability is 0.01 that a person living in the region will use sunscreen when going outdoors. (E) It is plausible that the percent of all people living in the region who regularly use sunscreen is 18.5%.

34. According to a recent report, customers who shop at a certain online store spend, on average, $1,500 a year at the store. To investigate whether the mean amount spent was greater than the reported average, an economist obtained the mean and standard deviation of the amount spent in the past year by a random sample of 120 customers who shop at the store. With all conditions for inference met, the economist conducted the appropriate hypothesis test and obtained a p-value of 0.25. Which of the following statements is the most appropriate conclusion for the investigation? (A) There is convincing statistical evidence that the mean amount of money spent each year by all customers who shop at the store is $1,500. (B) There is convincing statistical evidence that the mean amount of money spent each year by all customers who shop at the store is greater than $1,500. (C) There is convincing statistical evidence that the mean amount of money spent each year by all customers who shop at the store is less than $1,500. (D) There is not convincing statistical evidence that the mean amount of money spent each year by all customers who shop at the store is greater than $1,500. (E) There is not convincing statistical evidence that the mean amount of money spent each year by any sample of 120 customers who shop at the store is greater than $1,500.

35. Scientists working for a water district measure the water level in a lake each day. The daily water level in the lake varies due to weather conditions and other factors. The daily water level has a distribution that is approximately normal with mean water level of 84.07 feet. The probability that the daily water level in the lake is at least 100 feet is 0.064. Which of the following is closest to the probability that on a randomly selected day the water level in the lake will be at least 90 feet? (A) 0.29 (B) 0.31 (C) 0.34 (D) 0.37 (E) 0.50

36. The president of a large company recommends that employees perform, on average, 24 hours of community service each year. The president believes that the mean number of hours of community service performed last year was different from the recommended 24 hours. To estimate the mean number of hours of community service performed last year, the president obtained data from a random sample of employees and used the data to construct the 95 percent confidence interval (20.37, 23.49). If all conditions for inference were met, does the interval provide convincing statistical evidence, at a level of significance of a = 0.05, to support the president's belief that the mean number of hours of community service performed last year is different from what is recommended? (A) Yes, the interval supports the president's belief because 0 is not contained in the interval. (B) Yes, the interval supports the president's belief because 24 is not contained in the interval. (C) No, the interval does not support the president's belief because a 90% confidence interval is required for a 5% level of statistical evidence. (D) No, the interval does not support the president's belief because confidence intervals should only be used for. estimation and cannot provide convincing statistical evidence. (E) No, the interval does not support the president's belief because the significance level is equal to 1 minus the confidence level, indicating that the results are not convincing.

37. An international polling agency estimates that 36 percent of adults from Country X were first married between the ages of 18 and 32, and 26 percent of adults from Country Y were first married between the ages of 18 and 32. Based on the estimates, which of the following is closest to the probability that the difference in proportions between a random sample of 60 adults from Country X and a random sample of 50 adults from-Country Y (Country X minus Country Y) who were first married between the ages of 18 and 32 is greater than 0.15? (A) 0.1398 (B) 0.2843 (C) 0.4315 (D) 0.5685 (E) 0.7157

38. A consumer group wanted to investigate the relationship between the number of items purchased at a single visit to the local grocery store and the total cost of the items purchased. The group obtained a random sample of 11 receipts from the store and recorded the total number of items and the total cost from each receipt. The computer output of an analysis of total cost versus number of items purchased is shown in the table. Assume all conditions for inference were met. Based on the results shown in the table, which of the following is a 95 percent confidence interval for the average change in total cost for each increase of 1 item purchased? (A) 2.784 +- 12.29(0.2265) (B) 2.784 +- 2.262(0.2265) (C) 2.784 +- 2.262(0.2265/sqrt11) (D) 1.882 +- 1.96(6.6854) (E) 1.882 +- 2.262(6.6854)

39. A doctor uses a new diagnostic test to indicate whether a patient has a certain disease. The doctor will prescribe medication for the patient if the doctor believes the patient has the disease, as indicated by the diagnostic test. The situation is similar to using a null hypothesis and an alternative hypothesis to decide whether to prescribe the medication. The hypotheses can be stated as follows. Ho : The patient does not have the disease. Ha : The patient has the disease. Which of the following best describes the power of the test? (A) The probability that the new test is better than an older test to indicate whether a patient has the disease (B) The probability that the new test indicates the disease in a patient who has the disease (C) The probability that the new test indicates the disease in a patient who does not have the disease (D) The probability that the new test does not indicate the disease in a patient who has the disease (E) The probability that the new test does not indicate the disease in a patient who does not have the disease

40. To investigate the relationship between age and preference for two mayoral candidates in an upcoming election, a random sample of city residents was surveyed. The residents were asked which candidate they preferred, and each resident was classified into one of three age-groups. The test statistic for the appropriate hypothesis test was 3.7408. Approximately what is the probability that the observed responses would be as far or farther from the expected responses if there is no association between age-group and preference? (A) 0.0001 (B) 0.1541 (C) 0.2908 (D) 0.5873 (E) 0.7117