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: [230.375, -45.327, 112.137, 109.305]
Example Output: 101.622

Example Input: [193.711, 110.309, -20.334, 151.607, 158.797, -97.825, -59.931]
Example Output: 62.333

Example Input: [-55.579, 201.522, -89.814, 92.507, 213.802, -13.352, 184.884, -47.663, -96.205, 143.467]
Example Output:
53.357