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: [-70.638, 91.535, 238.435, 3.142, 229.662, 154.363, -34.792, -14.688, -18.959, 0.645]

57.871