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: [151.566, 66.145, 226.139, 96.531, -36.096, 56.396, -70.189, 208.907, 3.782]

78.131