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Restart your subscription to keep accessing solutions. Your Chegg Study subscription will expire on March 17, 2017. CONTINUE MY SUBSCRIPTION home / study / math / statistics and probability / questions and answers / a newly developed smartphone app is designed to ... Question: A newly developed smartphone app is designed to re... Bookmark A newly developed smartphone app is designed to retrieve prices and scheduling information for airline flights. Suppose we want to study how long it takes on average to retrieve this information. We record the processing time for 100 randomly selected flight searches. The sample statistics are: sample mean = 9.811 seconds and sample standard deviation = 2.972 seconds (Note: this SD is not the standard error of the mean, but rather the SD of the individual observations in the sample).

1) Give your answer as a properly formatted confidence interval statement. Choose the standard value for C.

Explanation / Answer

1) We calculate a 95% confidence interval for average

since, time taken follows Normal distribution with sample mean = 9.811 seconds and sample standard deviation = 2.972 seconds

Population standard devaition = sqrt(n-1/n)*sample standard devaition = sqrt(99/100)*2.972 = 2.9571

95% confidence interval is given by [mean-1.96*2.9571,mean + 1.96*2.9571]

ie. CI = [9.811-1.96*2.9571, 9.811 + 1.96*2.9571]

=[4.015084, 15.606916]

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