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: [49.462, -87.869, 36.985, 94.248, 175.789]
Example Output: 53.723

Example Input: [242.148, 97.472, -15.031, 246.784, 54.233, -27.114]
Example Output: 99.749

Example Input: [151.151, 144.049, 217.252]
Example Output:
170.817