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: [-6.982, 76.737, -68.014, 10.433, 229.902, 239.625, 15.505, -58.622, 90.128]

58.746