2. In a recent study of 53 ninth-grade students, the mean number of hours per week that they played video games was 72. The standard deviation of the population was 4.3. Find the 84% confidence interval for the mean of the time playing video games. 3. How large a sample is needed to estimate, with 91% confidence, the average number of minutes per day a person spends on the internet within 5 minutes? The population standard deviation is 37 minutes