A sample of 300 orders for? take-out food at a local pizzeria found that the average cost of an order was ?$24 with s=$13.

?(a) Find the margin of? error, if we use a? 95% confidence? interval, for the average cost of an order.

?(b) Interpret for management the margin of error.

?(c) If we need to be 99% confident, does the confidence interval become wider or? narrower?

?(d) Find the 99?% confidence interval.