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.

Example Input: [9.828, 248.054, 20.871, 99.749, 52.797, -86.856, 65.438, 53.627]
Example Output: 57.939

Example Input: [26.595, 220.402, -36.236, -79.382, -17.51, -71.282]
Example Output: 7.098

Example Input: [157.264, -70.245, -61.063, 5.07, 124.781, 203.599, 105.344, 174.924, 202.512, -82.565]
Example Output:
75.962