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: [19.96, 189.906, 247.19, 121.956, -1.653, -58.517, 79.039, 151.091, 26.034]

86.112