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: [61.739, -99.854, -53.677]
Example Output: -30.597

Example Input: [73.603, -84.154, 222.739, 205.594, 215.842]
Example Output: 126.725

Example Input: [32.459, -70.112, -49.429, 123.721, 95.856, 153.681, -38.965, 36.96, -1.414, 201.188]
Example Output:
48.395