AP Stats Ch. 10 Review

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.

 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 market researcher suspects that employees at Company A were older on average than employees at company B. They obtained a random sample of employees ages from each company. Results are shown. Which is the correct calculation for the t-statistic?

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Tags

CCSS.HSS.ID.A.4

A market researcher suspects that employees at Company A were older on average than employees at company B. They obtained a random sample of employees ages from each company. Results are shown. What should the researcher conclude at the 5% significance level?

• There is strong evidence that employees at company A are older than those at company B.

• There is strong evidence that employees at company B are older than those at company A.

• There is no difference in the ages of employees at companies A & B.

• The independent assumption is violated; no conclusions can be made.

To test a claim about a mean, when the population standard deviation is unknown we use:

• z procedures
• Pythagorean Theorem
• t procedures
• np > 10 and n(1-p) > 10

When p-value is greater than alpha we:

• Accept Ho
• Accept Ha
• Fail to reject Ho
• Reject Ho

Which of the following best describes a Type II error?

• The null is true but we mistakenly reject it.

• The null is false but we mistakenly reject it.

• The null is false but we fail to reject it.

• The null is true but we fail to reject it.

Tags

CCSS.HSS.MD.B.7

What is the Power of a test?

• A strong force
• The probability that we correctly reject a false null.
• The probability that we correctly accept a true null.
• How tough it is.

The reason we use t procedures instead of z procedures when carrying out a test about a population mean is that

• z requires that the sample size be large

• z requires that you know the population standard deviation σ

• z requires that the data come from a random sample or randomized experiment

• z requires that the population distribution be perfectly Normal

• z can only be used for proportion