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: [-31.252, 246.934, 96.512, 19.356, -50.759, 134.528, 176.914, 17.007, 171.802]
Example Output: 86.782

Example Input: [-84.771, 60.727, 165.566, 27.782, 159.929, 167.451, -64.15]
Example Output: 61.791

Example Input: [182.258, -29.431, 183.159, 213.025, -52.846, 107.38, 57.19]
Example Output:
94.391