2002 ap 统计真题.pdf

2002 AP 真题 1 STATISTICS SECTION I Time – 90 minutes Number of questions – 40 Percent of total grade – 50 FORM A Directions: Solve each of the following problems, using the available space for scratchwork. Decide which is the best of the choices given and fill in the corresponding oval on the answer sheet. No credit will be given for anything written in the test book. Do not spend too much time on any one problem. 1. Which of the following is a key distinction between well designed experiments and observational studies? (A) More subjects are available for experiments than for observational studies. (B) Ethical constraints prevent large-scale observational studies. (C) Experiments are less costly to conduct than observational studies. (D) An experiment can show a direct cause-and-effect relationship, whereas an observational study cannot. (E) Tests of significance cannot be used on data collected from an observational study. 2. Lauren is enrolled in a very large college calculus class. On the first exam, the class mean was 75 and the standard deviation was 10. On the second exam, the class mean was 70 and the standard deviation was 15. Lauren scored 85 on both exams. Assuming the scores on each exam were approximately normally distributed, on which exam did Lauren score better relative to the rest of the class? (A) She scored much better on the first exam. (B) She scored much better on the second exam. (C) She scored about equally well on both exams. (D) It is impossible to tell because the class size is not given. (E) It is impossible to tell because the correlation between the two sets of exam scores is not given. 2002 AP 真题 2 3. The number of sweatshirts a vendor sells daily has the following probability distribution. Number of Sweatshirts x 0 1 2 3 4 5 )(xP 0.3 0.2 0.3 0.1 0.08 0.02 If each sweatshirt sells for $25, what is the expected daily total dollar amount taken in by the vendor from the sale of sweatshirts? (A) $5.00 (B) $7.60 (C) $35.50 (D) $38.00 (E) $75.00 4. Suppose that the distribution of a set of scores has a mean of 47 and a standard deviation of 14. If 4 is added to each score, what will be the mean and the standard deviation of the distribution of new scores? Mean Standard Deviation (A) 51 14 (B) 51 18 (C) 47 14 (D) 47 16 (E) 47 18 5. A volunteer for a mayoral candidate’s campaign periodically conducts polls to estimate the proportion of people in the city who are planning to vote for this candidate in the upcoming election. Two weeks before the election, the volunteer plans to double the sample size in the polls. The main purpose of this is to (A) reduce nonresponse bias (B) reduce the effects of confounding variables (C) reduce bias due to the interviewer effect (D) decrease the variability in the population (E) decrease the standard deviation of the sampling distribution of the sample proportion 2002 AP 真题 3 6. The following two-way table resulted form classifying each individual in a random sample of residents of a small city according to level of education (with categories “earned at least a high school diploma” and “did not earn a high school diploma”) and employment status (with categories “employed full time” and “not employed full time”). Employed full time Not employed full time Total Earned at least a high school diploma 52 40 92 Did not earn a high school diploma 30 35 65 Total 82 75 157 If the null hypothesis of no association between level of education and employment status is true, which of the following expressions gives the expected number who earned at least a high school diploma and who are employed full time? (A) 157 5292 (B) 157 8292 (C) 92 5282 (D) 92 5265 (E) 82 5292 7. A random sample has been taken from a population. A statistician, using this sample, needs to decide whether to construct a 90 percent confidence interval for the population mean or a 95 percent confidence interval for the population mean. How will these intervals differ? (A) The 90 percent confidence interval will not be as wide as the 95 percent confidence interval. (B) The 90 percent confidence interval will be wider than the 95% confidence interval. (C) Which interval is wider will depend on how large the sample is. (D) Which interval is wider will depend on whether the sample is unbiased. (E) Which interval is wider will depend on whether a z-statistic or a t-statistic is used. 2002 AP 真题 4 8. A high school statistics class wants to conduct a survey to determine what percentage of students in the school would be willing to pay a fee for participating in after-school activities. Twenty students are randomly selected from each of the freshman, sophomore, junior and senior classes to complete the survey. This plan is an example of which type of sampling? (A) Cluster (B) Convenience (C) Simple random (D) Stratified random (E) Systematic 9. A least squared regression line was fitted to the weights (in pounds) versus age (in months) for a group of many young children. The equation of the li。