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: [16.517, -18.972, 7.067, 182.105, 4.053, 142.889, 236.815, 69.223, 67.278, -11.919]

69.506