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: [239.972, -40.003, 90.667, 218.19, 160.467, -38.168, 219.806]

121.562