Sampling plan for a movie promotion. Advertising companies often try to characterize the average user of a client's product so ads can be targeted at particular segments of the buying community. A new movie is about to be released, and the advertising company wants to determine whether to aim the ad campaign at people under or over 25 years of age. It plans to arrange an advance showing of the movie to an audience from each group and the obtain an opinion about the movie from each individual. How many individuals should be included in each sample if the advertising company wants to estimate the difference in the proportions of viewers in each age group who will like the movie to within .05 with 90% confidence? Assume the sample size for each group will be the same and about half of each group will like the movie.