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: [-21.313, 57.774, 94.232, 82.474, -60.586, 190.687, 180.63]

74.843