AP Stats Stats: Evaluation Overview 3

Question 1

When comparing the mean and median of a right-skewed distribution, which statement is typically true?

Accepted Answer

Mean > Median

Answer

In a right-skewed distribution, the long tail pulls the mean toward higher values, so mean > median.

Question 2

A student calculates r² = 0.81 for a linear regression. What does this mean?

Accepted Answer

81% of the variation in y is explained by the linear relationship with x

Answer

R-squared represents the proportion of variability in the response variable explained by the least-squares regression on the explanatory variable.

Question 3

In a two-sample t-test, what does the null hypothesis typically state?

Accepted Answer

μ₁ - μ₂ = 0

Answer

The null hypothesis for a two-sample t-test states there is no difference between the two population means (μ₁ - μ₂ = 0).

Question 4

Which of the following sampling methods is most likely to produce a biased sample?

Accepted Answer

Voluntary response sample

Answer

Voluntary response samples are biased because people with strong opinions are more likely to respond, making the sample unrepresentative.

Question 5

The standard error of a sample mean is calculated as:

Accepted Answer

s / √n

Answer

The standard error of the sample mean is the sample standard deviation divided by the square root of the sample size.

AP Practice Test