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: [157.631, 106.369, -25.319, 160.78, -87.597, 222.819, -60.99, 36.758, -3.695]

56.306