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: [-3.307, 140.293, 3.486, 62.844, 64.034, 157.329, 155.205, 68.587, 34.966]

75.937