Definition: In this task you will be given a list of numbers and you need to find the mean (average) of that list. The mean of a list can be found by summing every number in the list then dividing the result by the size of that list. The output should be rounded to 3 decimal places.
Input: [32.761, -85.094, -14.165, 82.742, -62.362, -62.383, -77.496, 139.749, -21.633]

-7.542