AP Statistics TOPIC A - Unit 2 MULTIPLE CHOICE

Transcription

1 AP Statistics TOPIC A - Unit 2 MULTIPLE CHOICE Name Date 1) True or False: In a normal distribution, the mean, median and mode all have the same value and the graph of the distribution is symmetric. 2) What 2 population parameters determine the shape of the normal curve? (they make the curve tall and skinny or short and fat) a) median and mean b) mode and standard deviation c) median and standard deviation d) mean and mode e) mean and standard deviation 3) Suppose a population of individuals has a mean weight of 160 pounds, with a population standard deviation of 30 pounds. According the Empirical Rule, what percent of the population would be between 100 and 220 pounds? a) 10% b) 68% c) 95% d) 99.7% e) None of the above For questions 4 and 5, use the following information: A population of bolts has a mean thickness of 20 millimeters with a standard deviation of 0.01 millimeters. 4) Give in millimeters, a minimum and a maximum thickness that includes 68% of the population of bolts. a) 20 to mm b) 19 to 21 mm c) to mm d) to mm e) to mm

2 5) Give in mm, a minimum and maximum thickness that will include 95% of the population of bolts. a) to mm b) to mm c) to mm d) 19.8 to 20.2 mm e) these can t be accurately computed 6) True or False: The point where the tails of a normal curve reach the x axis is the exact point where the upper and lower extremes of the population are located. 7) True or False: The area between ±2 standard deviations under the mean of a normal curve is approximately 95% of the total curve area. Also there is a 95% chance that an observation will be within ±2 standard deviations of the mean. For questions 8-11, use the following information: You measured the weights of members of population W and found the weights to be normally distributed. The distribution has a population mean (μ) weight of 160 pounds and a population standard deviation (σ) of 25 pounds. 8) For population W how many standard deviations from the mean is the weight of 185 pounds? a) -1σ b) 1σ c) 2σ d) 0σ e) -2σ 9) For population W, find the z score associated with a weight of 120 pounds. a) -2.6 b) -1 c) -1.6 d) 1 e) ) For population W, what is the percentile for the weight of 160 pounds? a) 50 th b) 10 th c) 30 th d) 75 th e) 90 th

3 11) In population W, what is the probability, to the nearest tenth of a percent, that a randomly selected student will weigh between 140 and 180 pounds? a) 20.2% b) 50% c) 67.7% d) 95% e) 57.6% 12) To the nearest whole number, what percentile is associated with z = -.68? a) 10 th b) 40 th c) 50 th d) 25 th e) 75 th Use the following information to answer questions 13-16: Applicants to a psychology department have normally distributed GRE scores with a mean, μ, of 544 and a standard deviation, σ, of ) What percentage of applicants scored between 500 and 700? Round to the nearest percent. a) 50% b) 60% c) 70% d) 80% e) 90% 14) What percentage of applicants scored above 450 on the GRE? Round to the nearest percent. a) 82% b) -82% c) 26% d) 11% e) 1% 15) What percentage of applicants has a GRE score below 625? (nearest percent) a) 78% b) -24% c) 24% d) 22% e) 5% 16) What is the GRE score at the 77 th percentile? (nearest whole number) a) 468 b) 505 c) 620 d) 1 e) -1 17) For a normal distribution with mean 480 and standard deviation 32, find the values for Q1, Q2, and Q3. a) 502, 458, 480 b) 458, 480, 502 c) 400, 500, 600 d) It depends on the standard deviation and the mean. e) It depends on the size of the population.

4 18) Consider a normal distribution with μ = 65 and σ = 4. A sample of size 950 is drawn from this population. Approximately how many of the 950 cases would you expect to find between 57 and 73? a) 646 b) 903 c) 947 d) All of them e) There isn t enough information to tell 19) The empirical rule indicates that roughly 47.5% of the observations in a normal distribution are located in the range between a z score of? a) 0,1 b) -1,1 c) 1,3 d) 0,-1 e) 0,-2 20) A normal curve table tells you that the probability lying below z = -1 is This can be interpreted as: a) 15.87% of the area of the curve lies below z = -1 b) 15.87% of the area under the curve lies at or below z = -1 c) A random selection from the population has a 15.87% chance of being below z = -1 d) A randomly selected from the population has a 15.87% chance of being at or below z = -1 e) All of the above. 21) Which of the following distributions is the least likely to fit a normal distribution? a) distribution of the heights of professional soccer players b) distribution of the lengths of salmon in the Pacific Ocean c) distribution of test scores among those who took the SATs in 1998 d) distribution of the ages of automobiles in driveable condition e) distribution of the points scored by a basketball player per game

5 22) You observe that the distribution of weights of individuals drawn from a random sample of the US appears bimodal; there are peaks at 130 lbs and 165 lbs. You were under the impression that weights follow a normal distribution. Why do you think this differs? a) The sample is not representative of the population. b) Individuals weights better fit a uniform distribution. c) The standard deviation of weights is greater than the mean weight. d) The sample is comprised of males and females. e) none of the above 23) You have 2 normally distributed populations: Population A: μ = 50 σ = 12 Population B: μ = 75 σ = 15 The area under the normal curve is greatest in which scenario? a) area below a value of 25 in population A b) area above 65 in population A c) area between 75 and 90 in population B d) area below 60 in population B e) area above 80 in population B