Medal
In a sample of 200 households, the mean number of hours spent on social networking sites during the month of January was 55 hours. In a much larger study, the standard deviation was determined to be 7 hours. Assume the population standard deviation is the same. What is the 99% confidence interval for the mean hours devoted to social networking in January?
The 99% confidence interval ranges from 53.73 to 56.27 hours.
The 99% confidence interval ranges from 7 to 55 hours.
The 99% confidence interval ranges from 54.51 to 55.49.
The 99% confidence interval ranges from 55 to 60 hours.

Question

Medal
In a sample of 200 households, the mean number of hours spent on social networking sites during the month of January was 55 hours. In a much larger study, the standard deviation was determined to be 7 hours. Assume the population standard deviation is the same. What is the 99% confidence interval for the mean hours devoted to social networking in January? 
The 99% confidence interval ranges from 53.73 to 56.27 hours. 
The 99% confidence interval ranges from 7 to 55 hours.
 The 99% confidence interval ranges from 54.51 to 55.49.
 The 99% confidence interval ranges from 55 to 60 hours.