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: [-84.257, 150.346, 115.489, 233.173, -21.974, -78.979, 60.098, 122.944, 41.603]

59.827