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: [186.393, -36.585, 69.153, 218.193, 218.362, 128.006, -68.039, 46.102, 131.093]

99.186