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: [58.76, -68.416, -56.764, 23.886, -52.382, 15.946, 128.488, 249.664, 206.743, 138.597]

64.452