Question 8.38

8.38 Instant versus fresh-brewed coffee.

A matched pairs experiment compares the taste of instant coffee with fresh-brewed coffee. Each subject tastes two unmarked cups of coffee, one of each type, in random order and states which he or she prefers. Of the 50 subjects who participate in the study, 19 prefer the instant coffee and the other 31 prefer fresh-brewed. Take to be the proportion of the population that prefers fresh-brewed coffee.

  1. Test the claim that a majority of people prefer the taste of fresh-brewed coffee. Report the statistic and its -value. Is your result significant at the 5% level? What is your practical conclusion?
  2. Find a 90% confidence interval for .