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: [38.459, -46.303, 155.479, 145.619, 154.178, 205.646, -99.859]

79.031