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: [155.894, 62.071, 211.995, 155.068, 206.305, 54.907, -92.807, -69.799, 111.639]

88.364