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: [-88.234, 220.691, 116.056, 148.231, 68.146, 82.137, 221.82, 200.488, 80.729]

116.674