<u>Answer</u>: No, we do not have sufficient evidence to conclude that the mean call duration, µ, is different from the 2010 mean of 9.4 minutes.
Step-by-step explanation:
As per given , we have
, since
is two-tailed so , the test is a two tail test.
Since population standard deviation is unknown, so we use t-test.
Critical value (two-tailed) for significance level of 0.01=
For n =50 , and s= 4.8
Test statistic :
Since test statistic value (-1.18) lies in critical interval (-2.609228, 2.609228), it means the null hypothesis is failed to reject.
We do not have sufficient evidence to conclude that the mean call duration, µ, is different from the 2010 mean of 9.4 minutes.