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: [58.978, 130.099, 69.294, 221.896, 145.41, 24.831, 59.427, 198.174, 146.553]

117.185