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: [-38.597, 140.983, 167.528, 81.287, -5.018, 236.15, 129.309, -39.064, 191.674, -87.769]

77.648