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: [191.229, -4.985, -59.758, 248.142, -58.435, -13.462, 141.933, -54.943, -26.838]

40.32