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: [176.555, -42.921, 234.9, -77.061, 195.761, 39.45, 190.59, 176.731, 172.393]

118.489