With this one question so much in advance yall : -)

Confidence interval: (21.9, 32.9).

Step-by-step explanation:

We have the standard deviation for the sample, which means that the t-distribution is used to solve this question.

The first step to solve this problem is finding how many degrees of freedom, we have. This is the sample size subtracted by 1. So

df = 26 - 1 = 25

98% confidence interval

Now, we have to find a value of T, which is found looking at the t table, with 25 degrees of freedom(y-axis) and a confidence level of . So we have T = 2.485

The margin of error is:

In which s is the standard deviation of the sample and n is the size of the sample.

The lower end of the interval is the sample mean subtracted by M. So it is 27.4 - 5.5 = 21.9 hours

The upper end of the interval is the sample mean added to M. So it is 27.4 + 5.5 = 32.9 hours

Confidence interval: (21.9, 32.9).