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: [227.405, 36.776, -56.411, 95.299, 88.066, -9.451, 170.481]

78.881