Students are asked about the number of songs they download from a pay-for-songs web site last month. From a random sample of 20 students, the sample mean was 4.7 and the sample standard deviation was 3.2. (Assume that the population is normally distributed) a. (6 points) Find the 95% confidence interval for u, the mean number of songs downloaded by the population of all students. Show your work! b. (4 points) Interpret the confidence interval