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: [-51.603, 117.351, -67.451, 218.664, 68.981, 167.005, -53.851, 104.996]
Example Output: 63.012

Example Input: [138.602, 158.458, 241.327, 194.509, 169.45, -56.151]
Example Output: 141.032

Example Input: [183.176, 235.514, 49.628]
Example Output:
156.106