Determine the margin of error for a confidence interval to estimate the population mean with n=18 and s= 15.4 for the confidence levels below.

a)80%

b)90%

c)99%

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Suppose a retailer claims that the average wait time for a customer on its support line is 185 seconds. A random sample of 54 customers had an average wait time of 176 seconds. Assume the population standard deviation for wait time is 47 seconds. Using a 95% confidenceinterval, does this sample support theretailer's claim?

Using a 95% confidenceinterval, does this sample support theretailer's claim? Select the correct choicebelow, and fill in the answer boxes to complete your choice.

(Round to two decimal places asneeded.)

A.

No, because theretailer's claim isnot between the lower limit of _________ seconds and the upper limit of ______ seconds for the mean wait time.

B.

Yes, because theretailer's claim is between the lower limit of

________ seconds and the upper limit of ________seconds for the mean wait time.

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Construct an 80% confidence interval to estimate the population mean using the data below.

x=23 s=4.4 n=14

What assumptions need to be made about thispopulation?

The 80% confidence interval for the population mean is from a lower limit of _________ to an upper limit of ______.