A 30-minute consumer survey mailed to 500 adults aged 25234 included a $10 gift certificate to Borders.

Question:

A 30-minute consumer survey mailed to 500 adults aged 25234 included a $10 gift certificate to Borders. The same survey was mailed to 500 adults aged 25234 without the gift certificate. There were 185 responses from the first group and 45 from the second group.
(a) At α = .025, did the gift certificate increase the response rate by more than 20 percent?
(b) Find the p-value.