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: [-17.379, 171.195, 66.643, 209.116, -91.047, 179.202, 214.886, 34.22, 238.33, 209.302]

121.447