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: [10.986, -94.96, 243.109, 12.322, -15.849, 166.927, 108.517, 79.409, 103.702, 209.938]

82.41