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: [239.17, 88.216, 6.914, -47.821, 77.692, 180.821, 116.501, -31.882]

78.701