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: [169.253, 248.402, 138.613, 144.26, 116.446, -20.712, 98.286, -38.63, 150.489]

111.823