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: [-43.315, 171.94, 167.346, -98.347, 71.547, -53.132, 175.534, 61.487, 155.516, -59.787]

54.879