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: [-29.727, 150.587, -28.344, 181.096, 0.275, -91.658, 169.609, -21.106, 153.48]
Example Output: 53.801

Example Input: [102.998, 85.82, -81.932, 145.893, 149.875, 243.316, -53.222, 163.536, 44.604]
Example Output:
88.988