A market research firm used a sample of individuals to rate the purchase potential of a particular product before and after the individuals saw a new television commercial about the product. The purchase potential ratings were based on a 0 to 10 scale, with higher values indicating a higher purchase potential. The null hypothesis stated that the mean rating "after" would be less than or equal to the mean rating "before." Rejection of this hypothesis would show that the commercial improved the mean purchase potential rating. Use = .05 and the following data to test the hypothesis and comment on the value of the commercial.

Purchase Rating Purchase Rating

Individual After Before Individual After Before

1 6 5 5 3 5

2 6 4 6 9 8

3 7 7 7 7 5

4 4 3 8 6 6

A. What are the hypotheses?

B. Compute ?? d (to 3 decimals).

Compute sd (to 1 decimal).