# AP Statistics : Measures of Distributions

## Example Questions

### Example Question #11 : Sampling Distributions

The purpose of the t test is to do which of the following?

Describe the variance within a population.

Determine the ability of one variable to predict another.

Test the relationship between five or more variables.

Compare the significance of multiple variables.

Compare the means of separate populations.

Compare the means of separate populations.

Explanation:

A t test is used to compare the means of different groups.  A t test score describes the likelihood that the difference in means between two groups is due to chance. The null hypothesis assumes the two sets are equal however, one can reject the null hypothesis with a p value within a particular confidence level.

### Example Question #181 : Ap Statistics

follows a chi-squared distribution with degrees of freedom and through are independent standard normal variables.

If , what is ?

Explanation:

Use the fact that the sum of  squared standard and independent normal variables follows a chi-squared distribution with degrees of freedom.