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: [218.711, -55.869, -23.387, 147.697, -19.716, 107.4, 73.115, 9.797, -58.891, 190.102]

58.896