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: [231.787, 146.369, -89.965, 171.172, -29.588, 87.013, -93.508]

60.469