To compare the effect of stress caused by noise on the ability to perform a simple task, 88 subjects were divided into two groups39 subjects as a control group, and 49 subjects as the experimental group. Although each subject performed the task, the experimental group had to perform the task while loud rock music was played. The time to finish the task was recorded for each subject and the following summary was obtained. Experimental 39 49 ; 16 minutes 23 minutes s 5 minutes 11 minutes (a) Find a 99% confidence interval for the difference in mean completion times (in minutes) for these two groups. (Calculate the difference as the control group the experimental group. Round your answers to two decimal places.) (b) Based on the confidence interval in part (a), is there sufficient evidence to indicate a difference in the average time to completion for the two groups? Explain. The condence interval in part (a) has . Hence, it is that the means are equal. Based on the data we would conclude that a real difference in the mean times to completion for the two groups