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: [102.998, 85.82, -81.932, 145.893, 149.875, 243.316, -53.222, 163.536, 44.604]

88.988