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: [87.234, -30.861, 221.46, 120.15, -85.065, 67.024, 144.174, -64.546]

57.446