15.

A clever undergraduate, grace n. Poise, hypothesizes that people under 30 are more humorous than people over 30. She tests this hypothesis by randomly selecting 4 people over 30 from the telephone book and 4 people under 30 from a university registration lists. She gives each research participant the humorous speech scale, which measures humor on a Likert-type scale from 1-10. The score listed below.

people under 30 People over 30

6 5

7 6

10 2

9 3

what is the t-value?