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: [-5.039, 100.623, 99.779, -1.782, 161.216, 79.249, -4.117, 173.877, 6.431, 202.513]

81.275