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: [140.276, -15.335, 193.793, 243.607, 133.838, 83.034, 98.676, 120.333, 89.905, 171.014]

125.914