In Order to Estimate the Average Time Spent Per Student

Multiple Choice

In order to estimate the average time spent per student on the computer terminals at a local university, data were collected for a sample of 81 business students over a one-week period.Assume the population standard deviation is 1.8 hours.If the sample mean is 9 hours, then the 95% confidence interval is

A) ​7.04 to 10.96 hours.
B) ​7.36 to 10.64 hours.
C) ​7.80 to 10.20 hours.
D) ​8.61 to 9.39 hours.