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: [130.499, 23.812, 188.301, 110.955, 131.399, 21.009, -0.771, -10.069, 198.135]

88.141