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: [211.362, 232.509, -55.576, 30.299, 166.106, 227.931, 229.432, 27.968, -25.196]

116.093