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: [238.489, 85.764, 219.917, 10.605, -15.771, -69.744, 183.494, -14.646, -14.628, 17.812]

64.129