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: [170.513, 92.657, -8.474, 126.75, 115.476, 75.692, 249.135, 86.047]

113.474