13. During the first 13 weeks of the television season, the Saturday evening 8:00 P.M. to 9:00 P.M. audience proportions were recorded as ABC 29%, CBS 28%, NBC 25%, and in- dependents 18%. A sample of 300 homes two weeks after a Saturday night schedule revi- sion yielded the following viewing audience data: ABC 95 homes, CBS 70 homes, NBC 89 homes, and independents 46 homes. Test with a = .05 to determine whether the view- ing audience proportions changed.