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: [-87.489, 33.74, 74.274, 95.47, -13.543, 240.068, 85.582, -44.767, 235.874, -99.599]

51.961