Definition: 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.
Input: [140.396, 51.9, -18.529, -74.292, 178.89, 197.292, 45.61, -29.629, 25.63]

57.474