3.1 A random sample of 49 lunch customers was taken at a restaurant. The average amount of time the customers in the sample stayed in the restaurant was 45 minutes with a variance of 196 minutes. a) Construct a 90% confidence interval for the true average amount of time customers spent in the restaurant. Construct a 99% confidence interval for the true average amount of time customers spent in the restaurant. With a 0.95 probability, how large of a sample would have to be taken to provide a margin of error of 2.5 minutes or less? (5) b) (5) c) (4)