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: [65.972, -62.482, -37.595, -68.513, 95.316, 53.128, -91.321]

-6.499