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: [-65.445, 3.537, 214.879, -67.657, -10.15, 43.522, 89.312, -58.043, 143.491, -89.705]

20.374