AP Statistics Chapter 7 Test Review Answers Concept

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AP Statistics Chapter 7 Test Review Answers

AP Statistics Chapter 7 Test Review Answers

Concept Question #1 •

Concept Question #1 •

Concept Question #2 • When we talk about the ‘variability’ of a statistic, then

Concept Question #2 • When we talk about the ‘variability’ of a statistic, then we are focusing on what aspect of a distribution? – ANSWER: The spread of the distribution.

Concept Question #3 • When we talk about the amount of “bias” in a

Concept Question #3 • When we talk about the amount of “bias” in a statistic, then what aspect of the distribution are we talking about? – ANSWER: The center of the distribution

Concept Question #4 • MULTIPLE CHOICE: Which of the following is the preferred characteristic

Concept Question #4 • MULTIPLE CHOICE: Which of the following is the preferred characteristic of an estimate of a parameter – A. A statistic with high variability and low bias – B. A statistic with high variability and high bias – C. A statistic with low variability and low bias – D. A statistic with low variability and high bias – E. It doesn’t matter how much bias or variability a statistic contains • ANSWER: C…. The less bias and variability… the better.

Concept Question #5 • If you wish to reduce the amount of variability in

Concept Question #5 • If you wish to reduce the amount of variability in a statistic that we hope to use to estimate a parameter, then what is the best way to accomplish this? – ANSWER: INCREASE the sample size.

Concept Question #6 •

Concept Question #6 •

Concept Question #7 •

Concept Question #7 •

Concept Question #8 •

Concept Question #8 •

Concept Question #9 •

Concept Question #9 •

Concept Question #10 •

Concept Question #10 •

Concept Question #11 • What is the ‘magic number’ that ensures that a sampling

Concept Question #11 • What is the ‘magic number’ that ensures that a sampling distribution (FOR MEANS) will be approximately normal, even if the parent population is highly skewed to the right? – ANSWER: According to the Central Limit Theorem, 30 is the ‘magic number’. – Note: DO NOT use the phrase ‘magic number’ in your answer to a FRQ on a test or on the AP EXAM…

Concept Question #12 • What EXACTLY is the condition (FOR PROPORTIONS) that must be

Concept Question #12 • What EXACTLY is the condition (FOR PROPORTIONS) that must be met in order to conclude that a ‘normal approximation’ can be made (i. e. : distribution is normal)? –ANSWER: n·p ≥ 10 AND n·q ≥ 10

Concept Question #13 •

Concept Question #13 •

Concept Question #14 •

Concept Question #14 •

Concept Question #15 • If we take many simple random samples (SRS’s) from the

Concept Question #15 • If we take many simple random samples (SRS’s) from the exact same population what do we expect to have happen? • ANSWER: The values of the statistics that we get from that population will vary from sample to sample.

Concept Question #16 •

Concept Question #16 •

Concept Question #17 • Which of the following best describes a sampling distribution? •

Concept Question #17 • Which of the following best describes a sampling distribution? • A. The distribution of all values of a statistic found in a large number of simulated samples of size n. • B. The set of all values of a variable in a sample of size n. • C. The set of all values of a variable in a large number of samples of size n. • D. The distribution of parameter values in all possible samples of size n. • E. A probability distribution that describes the relative likelihood of all possible values of a statistic. • Answer: E

Concept Question #18 • In a large population of adults, the mean IQ is

Concept Question #18 • In a large population of adults, the mean IQ is 112 with a standard deviation of 20. Suppose 200 adults are randomly selected for a market research campaign. The sampling distribution of the sample mean IQ is • A. exactly Normal, mean 112, standard deviation 20. • B. approximately Normal, mean 112, standard deviation 0. 1. • C. approximately Normal, mean 112, standard deviation 1. 414. • D. approximately Normal, mean 112, standard deviation 20. • E. exactly Normal, mean 112, standard deviation 1. 414. • ANSWER: C

Concept Question #19 • Suppose you are sampling from a distribution that is strongly

Concept Question #19 • Suppose you are sampling from a distribution that is strongly skewed left. Which of the following statements about the sampling distribution of the sample mean is true? • A. As the sample size increases, the shape of the sampling distribution gets closer and closer to a Normal distribution. • B. As the sample size increases, the shape of the sampling distribution gets closer and closer to the shape of the population distribution. • C. As the sample size increases, the mean of the sampling distribution gets closer to the population mean. • D. Regardless of the sample size, the shape of the sampling distribution is similar to the shape of the population distribution. • E. Regardless of the sample size, the standard deviation of the sampling distribution is approximately equal to the standard deviation of the population. • ANSWER: A

Concept Question #20 • Suppose we wish to estimate the percentage of students who

Concept Question #20 • Suppose we wish to estimate the percentage of students who smoke cigarettes at each of several colleges and universities. Two of the colleges are Wabash College (enrollment 900) and Purdue University (enrollment 36, 000). What should the relative size of our samples be from each school if we want the two sampling distributions to have approximately the same standard deviation? • A. Because the population sizes are so different, it’s impossible to make the standard deviations equal by adjusting the two sample sizes. • B. We should take a larger number of Purdue students, since there are more of them. • C. We should take a larger number of Wabash students, since there are fewer of them. • D. We should take the same size samples from each school. • E. We should take samples that are exactly 10% of each school’s enrollment. • ANSWER: D

Concept Question #21 • A statistic is said to be unbiased if • A.

Concept Question #21 • A statistic is said to be unbiased if • A. the survey used to obtain the statistic was designed so as to avoid even the hint of racial or sexual prejudice. • B. the mean of its sampling distribution is equal to the true value of the parameter being estimated. • C. both the person who calculated the statistic and the subjects whose responses make up the statistic were truthful. • D. the value from any sample is equal to the parameter being estimated. • E. it is used for honest purposes only. • ANSWER: B