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: [3.402, 123.403, 155.401, 193.566, 12.549, 194.144, 77.964, 65.128, 37.553, -73.981]

78.913