A high school teacher at a small private school assigns trigonometry practice problems to be worked via the net. Students must use a password to access the problems and the time of log-in and log-off are automatically recorded for the teacher. At the end of the week, the teacher examines the amount of time each student spent working the assigned problems. Based on past experiences, the standard deviation of the amount of time students spent answering an online problem is 9.918 minutes.

The data provided below in minutes.

42,43,29,47,49,42,22,46,34,21,27,38,35,33,21,20,21,45,49,

45,29,29,31,20,46,31,31,38,44,49,48,22

Construct a 99% confidence interval on the true average time the student spent working the assigned projects.

Express your answer in 3 decimal places:

1) Sample mean

2.) Error

3.) Confidence interval