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: [111.725, 198.334, 138.375, 10.272, 111.717, 63.948, -1.108, 148.762, 215.813]

110.871