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: [235.663, 221.742, 156.739, -86.57, 146.941, 40.07, -8.314]

100.896