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: [243.402, 228.627, -58.995, -42.118, 7.87, -36.229, 163.24, 47.454, 22.998, -43.723]

53.253