Some fast-food chains offer a lower-priced combination meal in an effort to attract budget-conscious customers. One chain tested a burger, chips and drink combination for $6.95. The weekly sales volume for these meals was impressive. Suppose the chain wants to estimate the average amount its customers spent (in dollars) on a meal at their restaurant while this combination offer was in effect. An analyst gathers data from 28 randomly selected customers. The following data represent the sample meal totals in dollars. The average spending from the sample is $7.87 and the sample standard deviation is $0.87.   Use the above information to construct a 90% confidence interval( Upper and lower Limit )  to estimate the population mean value in dollars. Assume that the amounts spent are normally distributed.