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: [159.301, 197.915, 139.146, 227.732, 123.147, 115.352, 213.182, -23.946, 111.067, 86.199]

134.91