AP Stats Stats: Key Skills Assessed 2

Question 1

A researcher collects data on reaction times (ms) for 50 subjects. The distribution is strongly right-skewed. Which measure of center best describes the data?

Accepted Answer

Median

Answer

Mean

Answer

Mode

Answer

Range

Question 2

When constructing a 95% confidence interval for a population mean, which of the following changes would decrease the margin of error?

Accepted Answer

Increasing the sample size

Answer

Increasing the confidence level to 99%

Answer

Decreasing the sample size

Answer

Increasing the population standard deviation

Question 3

A z-score of −2.1 for an observation means that the observation is:

Accepted Answer

2.1 standard deviations below the mean

Answer

2.1 units below the mean

Answer

2.1% below the mean

Answer

2.1 standard deviations above the mean

Question 4

In a two-sample t-test comparing group means, which condition is required for the test to be valid?

Accepted Answer

The two samples must be independent of each other

Answer

Both populations must be exactly normal

Answer

The samples must be collected from the same population

Answer

Both sample sizes must be equal

Question 5

A scatterplot shows a curved, nonlinear relationship between x and y. Which action is most appropriate before performing linear regression?

Accepted Answer

Apply a transformation such as log(y) or √y

Answer

Remove outliers from the dataset

Answer

Increase the sample size

Answer

Use a one-sample t-test instead

Question 6

A Type I error in hypothesis testing occurs when:

Accepted Answer

The null hypothesis is true and we reject it

Answer

The null hypothesis is false and we fail to reject it

Answer

The null hypothesis is true and we fail to reject it

Answer

The alternative hypothesis is true and we reject the null

Question 7

Which of the following best describes the power of a hypothesis test?

Accepted Answer

The probability of rejecting the null hypothesis when it is false

Answer

The probability of making a Type I error

Answer

The probability of failing to reject the null hypothesis when it is true

Answer

The width of the confidence interval