A random sample of20

subjects was asked to perform a given task. The time in seconds it took each of them to complete the task is recorded below:

26,43,41,25,41,25,50,42,36,42,50,29,34,32,32,32,48,47,38,31

If we assume that the completion times are normally distributed, find a95

%

confidence interval for the true mean completion time for this task. Then complete the table below.

What is the lower limit of the confidence interval?

What is the upper limit of the confidence interval?