Question

A certain organization wants to know the opinion of the adult residents, 35 years of age or older, of the xxx city with a total population of 55,000 about lowering the drinking age to 18

Answer 1

0.7 +/- 0.0635 is the answer. The confidence interval is

p±1.96√p(1−p)/n

p = 140/200 = 0.7 (the proportion in favor of lowering the drinking age) n = the sample size, 200 1.96 is the critical value for a 95% confidence interval, from the z-table (standard normal distribution)