in a sample of 100 households, the mean number of hours spent on social networking sites during the month of january was 50 hours. in a much larger study, the standard deviation was determined to be 6 hours. assume the population standard deviation is the same. what is the 98% confidence interval for the mean hours devoted to social networking in january? a. the 98% confidence interval ranges from 6 to 50 hours.
b. the 98% confidence interval ranges from 48.60 to 51.40 hours.
c. the 98% confidence interval ranges from 49.40 to 50.60 hours.
d. the 98% confidence interval ranges from 50 to 52 hours.