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: [215.161, 124.785, 203.26, 121.709, 161.316, 149.034, 108.509, -30.096, -63.199, 30.95]

102.143