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: [155.567, 46.373, 64.41, 45.766, 233.658, 109.22, 222.628, -6.498, -50.331]

91.199