Would you mind explaining to me the answer to this question, please?

A class survey in a large class for first-year college students asked, About how many hours do you study during a typical week? The mean response of the 463 students wasx= 15.3 hours.

Suppose that we know that the study time follows a Normal distribution with standard deviation= 8.5 hours in the population of all first-year students at this university.

Step 1:

Use the survey result to give a 99% confidence interval for the mean study time of all first-year students.24.08 to 28.92

14.98 to 21.02

14.28 to 16.32

17.64 to 18.36

What condition not yet mentioned is needed for your confidence interval to be valid?SRS.

Unknown.

Normal distribution.

Known.