A sample of 350 orders for take-out food at a local pizzeria found that the average cost of an order was $29 with s=$13.

One more question

A sample of 350 orders for take-out food at a local pizzeria found that the average cost of an order was $29 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.