Question

Jordan is the manager of a used book store. He wants to estimate the average amount a customer spends per visit. A random sample of 80 customer receipts showed a mean of ​$6.87 with a standard deviation of ​$2.49. Find a 95​% confidence interval for the average amount spent by all of his customers.  Include the interpretation of the interval.

​A) Confidence​ Interval: ( nothing ​, nothing ​) ​(round each interval limit to two decimal​ places) ​

B) In the SHOW YOUR WORK​ area, interpert the confidence interval you just found. ​(You do not need to show the StatCrunch​ output, just the​ interpretation.) ​

C) Jill's used book store has a mean of​ $5.25 per receipt. Is Jordan or Jill doing​ better?

A. Jordan is doing better because​ $5.25 is below the interval.

B. Jordan is doing better because​ $7.11 is greater than​ $5.25.

C. Jill is doing better because​ $5.25 is above the interval.

D. One cannot tell because​ $5.25 is within the interval.

Answer 1

A)

Confidence​ Interval: (6.32 ,7.42)

B)

Above interval gives 95% confidence to contain true population mean  amount spent by all of Jordan customers

C)

A. Jordan is doing better because​ $5.25 is below the interval.