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: [213.149, 184.894, -93.544, 195.043, 78.738, 229.09, 220.609, 80.079, 7.498]

123.951