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: [172.686, 46.972, 139.657, -30.122, 126.099, 89.965, 145.669]

98.704