Question

Suppose a retailer claims that the average wait time for a customer on its support line is 173 seconds. A random sample of 48 customers had an average wait time of 164 seconds. Assume the population standard deviation for wait time is 47 seconds. Using a 95​% confidence​ interval, does this sample support the​ retailer's claim?

Using a 95​% confidence​ interval, does this sample support the​ retailer's claim? Select the correct choice​ below, and fill in the answer boxes to complete your choice.

​(Round to two decimal places as​ needed.)

A. No​,because the​ retailer's claim is not between the lower limit of __ seconds and the upper limit of __ seconds for the mean wait time.

B. Yes​, because the​ retailer's claim is nothing between the lower limit of __ seconds and the upper limit of ___

seconds for the mean wait time.

Answer 1

95% confidence interval for is

- Z * / sqrt(n) < < + Z * / sqrt(n)

164 - 1.96 * 47 / sqrt(48) < < 164 + 1.96 * 47 / sqrt(48)

150.70 < < 177.30

95% CI is (150.70 , 177.30 )

Yes​, because the​ retailer's claim is between the lower limit of 150.70 seconds and the upper limit of 177.30

seconds for the mean wait time.