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: [-18.869, 50.266, 91.882, 220.184, 191.82, 224.977, -48.069]

101.742