GfK Roper Consulting gathers information on consumer preferences around the world to help companies monitor attitudes about health, food, and health care products. They asked people in many different cultures how they felt about the following statement: I try to avoid eating fast foods. In a random sample of 800 respondents, 411 people were 35 years old or younger, and, of those, 197 agreed (completely or somewhat) with the statement. Of the 389 people over 35 years old, 246 people agreed with the statement.
a) Is there evidence that the percentage of people avoiding fast food is different in the two age groups?
b) Give a 90% confidence interval for the difference in proportions.