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: [4.102, -87.542, -86.997, -15.641, 41.532, 101.529, 220.459]

25.349