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: [113.95, 191.136, 21.78, -84.56, 116.657, 28.424, 203.7, 153.447, 145.773]

98.923