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: [208.812, 24.785, 213.779, 188.42, 88.614, 128.372, 239.569, -64.778, 125.207]

128.087