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: [218.46, 7.937, 155.624, 82.813, 93.516]
Example Output: 111.67

Example Input: [-40.246, -7.512, 174.245, -98.6]
Example Output: 6.972

Example Input: [8.845, -28.978, -50.591, -2.116, 237.651, 247.451]
Example Output:
68.71

