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: [17.29, 6.639, 140.595, 18.134, 51.788, 30.284, -39.61, 241.772, 10.653]

53.061