A shopkeeper complains that the average weight of chocolate bars of a certain type that he is buying from a wholesaler is less than the stated value of 8.50g. The shop keeper weighed 100 bars from a large delivery and found that their weights had a mean of 8.36g and a standard deviation of 0.72g.

A) Using a 5% significance level, determine whether the shop keeper is justified in his complaint. (5 marks)

B) State clearly the null and alternate hypothesis that you are using and express your conclusion in words. (5 marks)

C) Obtain, to 2 decimal places, the limits of a 98% confidence interval for the mean weight of the chocolate bars in the shop keepers' delivery. (5 marks