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: [-45.826, -27.376, 126.782, -28.164, 213.819, 186.676]
Example Output: 70.985

Example Input: [-64.231, 200.235, -9.547, -98.817, 222.577, 12.8, 214.705, 122.883, 216.246, 113.126]
Example Output: 92.998

Example Input: [184.052, 172.283, 30.542, 193.486, -20.178, 186.059, 221.473, 222.066, 15.525]
Example Output:
133.923