If an independent samples of 70 recent prime time airings from each of two major networks have been considered. The first network aired a mean of 110.6 commercials during prime time, with a standard deviation of 4.3 commercials. second network aired a mean of 109.4 commercials, with a standard deviation of 4.9 commercials. As the sample sizes are quite large, the population standard deviations can be estimated using the sample standard deviations. Construct a 90% confidence interval for -μ1, μ2, the difference between the mean number of commercials μ1 aired during prime time by the first network and the mean number of commercials μ2 aired during prime time by the second network.
What is the lower limit of the 90% confidence interval?
What is the upper limit of the 90% confidence interval?