1. The manager of AllNeeds supermarket wants to estimate ,, the average amount of money spent per week for groceries by each student, assuming this amount of money follows approximately a normal distribution. A random sample of 90 is taken, of which the mean and standard deviation of the amount of money spent per week for groceries are GHC81.50 and GHC10.36 respectively. (a) Calculate a 99% confidence interval for . (b) Based on your result in (i), would you say on average a student spends more than GHC30? (c) How many students must be surveyed if the manager wanted to estimate the true average spending of students within a margin of .10 with probability .95? 2. Independent random samples from normal distributions with equal variance of the amount of insider trading during mergers by employees of investment banking firms (1) and brokerage houses (2) gave the results listed in the accompanying table. Investment Banking Firm Brokerage House 10 5 5 5 88 605 2 2 3 3 (a) Find the 95% confidence interval estimate for the difference between means 2.. (b) Would you conclude that employees of Investment banking firms cause more insider trading than their counterparts in Brokerage House