A taste-testing experiment compared two brands of Chilean merlot wines. After the initial comparison, 60 preferred Brand A, and 40 preferred Brand B. The 100 respondents were then exposed to a very professional and powerful advertisement promoting Brand A. The 100 respondents were then asked to taste the two wines again and declare which brand they preferred. The results are shown in the following table:

a. At the 0.05 level of significance, is there evidence that the proportion who preferred Brand A was lower before the advertising than after the advertising?
b. Compute the p-value in (a) and interpret its meaning.

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PREFERENCE AFTER ADVERTISING PREFERENCE PRIOR TO ADVERTISING Brand A Brand B Total Brand A Brand B Total 15 70 25 30 60 40 100