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: [141.767, 179.216, -65.681, 220.694, 218.833, -91.372, -95.051, 175.189, 131.244]

90.538