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: [214.433, 229.507, 126.45, 124.396, -41.413, 43.572, 165.134]

123.154