AP Stats Chapter 10

A track and field coach wants to find out whether a particular hammer thrower performs better, on average, in the morning throws or in the afternoon. The coach observes a random sample of the athlete's throws in the morning and a random sample of the athlete's afternoon throws. Which of the following significance tests could be used to analyze the results?

• One-sample t-test for a mean

• Two-sample t-test for means

• Paired t-test

• One-proportion z-test

• Two-proportion z-test

At a baseball game, 42 of 65 randomly selected people own an iPod. At a rock concert occurring at the same time across town, 34 of 52 randomly selected people own an iPod. A researcher wants to test the claim that the proportion of iPod owners at the two venues is different. A 90% confidence interval for the difference in population proportions(game − concert) is (−0.154, 0.138). Which of the following gives the correct outcome of the researcher’s test of the claim?

• Because the confidence interval includes 0, the researcher can conclude that the proportion of iPod owners at the two venues is the same.
• Because the center of the interval is –0.008, the researcher can conclude that a higher proportion of people at the rock concert own iPods than at the baseball game.
• Because the confidence interval includes 0, the researcher cannot conclude that the proportion of iPod owners at the two venues is different.
• Because the confidence interval includes more negative than positive values, the researcher can conclude that a higher proportion of people at the rock concert own iPods than at the baseball game.

For a simple random sample of 100 cars of a certain popular model in 2012, it was found that 20 had a certain minor defect in the brakes. For an independent SRS of 400 cars of the same model in 2009, it was found that 50 had the same defect. A 90% confidence interval for p₂₀₁₂– p₂₀₀₉ is (approximately)

• 0.075 ± 0.085
• 0.075 ± 0.071
• 0.075 ± 0.043

 In a simple random sample of 100 cars of a certain popular model in 2010, it was found that 20 had a certain minor defect in the brakes. For an independent SRS of 400 cars of the same model in 2011, it was found that 50 had the same defect. Let p₁ and p₂ be the proportions of all cars of this model in 2010 and 2011, respectively, that have the defect. We wish to test H₀ : p₁ - p₂ = 0 against H_A : p₁ - p₂ > 0 . Which of the following is closest to the P-value for this test?

• 0.0418
• 0.0536
• 0.0268

A manufacturer receives parts from two suppliers. An SRS of 400 parts from Supplier 1 contains 20 defective parts, while an independent SRS of 100 parts from Supplier 2 contains 10 defective parts. Let p₁ and p₂ be the proportions of defective parts made by Supplier 1 and Supplier 2, respectively. Is there evidence of a significant difference in the proportions of defective parts made by these two suppliers? To answer this question, you test the hypotheses H₀ : p₁ - p₂ = 0 against H_A : p₁ - p₂  ≠ 0 . Which of the following is closest to the P-value of the test?

• 0.9398
• 0.0602
• 0.0301

The NCAA requires colleges to report the graduation rates of their athletes. One Big Ten university reported that the graduation rates for a specific year were 21 of 28 females athletes and 24 of 46 male athletes. Is there evidence that a smaller proportion of male athletes than of female athletes graduate?

• 1-sample t-test

• 1-sample t-test (mean difference)

• 2-sample t-test (difference in means)

• 2-proportion z-test

A famous medical experiment was conducted by the Nobel Laureate Linus Pauling who believed that vitamin C prevents colds. His subjects were 279 French skiers who were randomly assigned to receive vitamin C or a placebo. Of the 139 given vitamin C, 17 got a cold. Of the 140 given the placebo, 31 got a cold. Find and interpret a 95% confidence interval for the difference of two proportions.

• 1-sample t-interval(mean difference)

• 1-proportion z-interval

• 2-sample t-interval (difference in means)

• 2-proportion z-interval

A study on facial expression and anxiety was conducted to determine if anxious people exhibit more or fewer facial expressions compared to non-anxious people. The number of facial expressions exhibited in response to 25 emotional cues for 25 anxious subjects and 25 non-anxious subjects are collected. Will anxious people exhibit a different number of facial expressions compared to non-anxious people?

• 1-sample t-test

• 1-sample t-test (mean difference)

• 2-sample t-test (difference in means)

A study of road rage asked separate random samples of 596 men and 523 women about their behavior while driving. Based on their answers, each respondent was assigned a road rage score on a scale of 0 to 20. Are the conditions for performing a two-sample t test satisfied?

• Yes; we have two independent random samples and large samples.

• Maybe; we have independent random samples, but we need to look at the data to check for Normality.

• No; road rage scores in a range between 0 and 20 can't be Normal.

• No; we don't know the population standard deviation.

• Yes; the large sample sizes guarantee that the corresponding population distributions will be Normal.

• a

• b

• c

• d

• e