8.5 The weights of bags of pears sold to customers asking for one pound of pears at a market stall is known to be Normally distributed. The weights of bags served to a random sample of 15 customers were measured. The sample mean weight was 1.06 lb with a standard deviation of 0.11 lb.

(a) Produce a 95 per cent confidence interval for the weight of ‘one pound’ bags of pears.

(b) Produce a 99 per cent confidence interval for the weight of ‘one pound’ bags of pears.