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: [51.372, 141.276, 8.131, 168.539, 151.323]
Example Output: 104.128

Example Input: [-60.041, -56.779, 6.2, 73.114, 137.319]
Example Output: 19.963

Example Input: [207.704, 128.408, 59.125]
Example Output:
131.746

