In order to estimate the average time spent on the computer terminals per student at a local university, data were collected from a sample of 81 business students over a one-week period. Assume the population standard deviation is 1.2 hours. If the sample mean is 9 hours, then the 95% confidence interval is approximately . a. 7.80 to 10.20 hours b. 8.74 to 9.26 hours c. 7.36 to 10.64 hours d. 7.04 to 110.96 hours