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: [124.333, 5.477, -53.787, 226.538, -40.577, -43.102, 214.118, 125.785, 151.837]

78.958