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: [2.737, -21.279, -99.368, 87.158, 113.644, 114.376, -4.483]

27.541