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: [221.679, 16.334, 157.622, 118.18, 168.849, 157.974, 37.636, 249.085, -10.276, 70.5]

118.758