The list below shows the length in days of each of the space shuttle Endeavour's missions.

10, 9, 7, 11, 12, 12, 12, 17, 12, 10, 11, 10, 12, 12, 12, 13, 13, 13, 15, 14, 16, 17, 17, 14, 17

Calculate the following to help analyze the data set. If the answer is not a whole number, use a decimal.