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: [215.087, 73.727, 216.959, 186.669, 53.779, 177.474, 79.12, 237.295, 109.343]

149.939