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: [112.134, 102.301, 12.44, 102.084, 146.014, -21.711, 145.399]

85.523