Please help I don't understand.

5 . (15 pts) A marketing firm wants to know the average amount of time young adults (18 to 25-year- olds) spend watching Netflix each day. A survey is completed by 75 young adults and the mean time spent watching Netflix is found to be 162.5 minutes with a standard deviation of 40 minutes. a. Construct a 95% confidence interval for the mean amount of time that young adults spend watching Netflix each day. (Round your answer to 3 decimal places) b. Explain in words what this confidence interval means. c. How many young adults would need to be surveyed to have a margin of error of 2