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: [-47.917, -46.834, 56.498, 201.571, -36.733, -64.537, 87.826]

21.411