Sam is the manager of a used clothing store. He wants to estimate the average amount a customer spends per visit. A random sample of 70 customers’ receipts gave a mean of = $7.10 with a standard...

Sam is the manager of a used clothing store.  He wants to estimate the average amount a customer spends per visit.  A random sample of 70 customers’ receipts gave a mean of = $7.10 with a standard deviation s = $2.30.  Find a 99% confidence interval for the average amount spent by all customers. Interpret your findings.