D Question 9 16 pts Jordan is the manager of a used book store. He knows that the amount of a customer spends per visit approaches a normal distribution. Now, he wants to estimate the average amount a customer spends per visit. A random sample of 20 customer receipts had a mean of $6.90. Based on prior information, the population standard deviation is $2.45. Find a 90% confidence interval for the average amount spent by all customers. (You need to write out your answer in the following textbox.) Edit View Insert Format Tools Table