In 2002, the average duration of incoming telephone calls to a furniture store was 9.4 minutes. The manager wants to perform a test to determine whether this average duration of incoming calls has changed. Twenty calls to the store were randomly selected and the mean duration was 10.2 minutes with standard deviation 4.8 minutes. Assuming that the duration of incoming telephone calls to a furniture store is normally distributed, a) Using a 1% level of significance, test whether the mean duration of incoming calls to the store had changed.  b) Construct the 95% confidence interval for the population mean duration of the incoming calls to the furniture store.

Glencoe Algebra 1, Student Edition, 9780079039897, 0079039898, 2018
18th Edition
ISBN:9780079039897
Author:Carter
Publisher:Carter
Chapter10: Statistics
Section10.6: Summarizing Categorical Data
Problem 30PPS
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In 2002, the average duration of incoming telephone calls to a furniture store was 9.4 minutes. The manager
wants to perform a test to determine whether this average duration of incoming calls has changed. Twenty
calls to the store were randomly selected and the mean duration was 10.2 minutes with standard deviation
4.8 minutes. Assuming that the duration of incoming telephone calls to a furniture store is normally
distributed,
a) Using a 1% level of significance, test whether the mean duration of incoming calls to the store had
changed. 
b) Construct the 95% confidence interval for the population mean duration of the incoming calls to
the furniture store. 

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