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: [213.2, 159.287, 214.859, 189.464, 185.706, -85.847, 215.647, 8.545]

137.608