Long Quiz

The mean and standard deviation of a population are 400 and 40, respectively. Sample size is 25. What is the mean of the sampling distribution?

• 400

• 25

• 40

• 8

Answer explanation

The mean of the sampling distribution is equal to the mean of the population.

The mean and standard deviation of a population are 400 and 40, respectively. Sample size is 25.  What is the standard error of the sampling distribution?

• 400

• 25

• 40

• 8

Answer explanation

The standard deviation of the sampling distribution is equal to the population standard deviation divided by the square root of sample size.

These symbols represent the mean and standard deviation for which of the following distributions?

• The Population

• The Sampling Distribution

• The Sample

• The Statistic

Answer explanation

True or False:

As the sample size n increases without limit, the shape of the distribution becomes less normal.

• True

• False

Answer explanation

As the sample size n increases without limit, the shape of the distribution becomes normal.

The variance of the sampling distribution is equal to the population variance multiplied by the sample size.

• True

• False

Answer explanation

The variance of the sampling distribution is equal to the population variance divided by the sample size.

A population has a standard deviation of σ = 17.3. How large of a sample must be drawn so that a 95% confidence interval for µ (confidence coefficient=1.96) will have a Margin of Error equal to 1.4?

• 586.6

• 586

• 587

• 585

Answer explanation

True or False: The more confident you want to be, the smaller your confidence interval will be.

• True

• False

Answer explanation

The more confident you want to be, the larger your confidence interval will be.

Which of the following changes to a study would result in a smaller confidence interval?

• increasing the confidence level, increasing the sample size

• decreasing the confidence level, decreasing the sample size

• increasing the confidence level, decreasing the sample size

• decreasing the confidence level, increasing the sample size.

A research company wants to estimate the proportion of people who like oatmeal. They want the confidence level to be 95%. The company gets 325 people to sign up for the survey, but on the day that the survey is issued, only 250 people show up and take the survey. What happens to the confidence interval?

• It stays the same

• It gets larger

• It gets smaller

• Not enough information

What is the right-tailed area if the confidence interval is 75%?

• 0.005

• 0.10

• 0.05

• 0.25

Answer explanation