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: [73.888, 3.603, -39.616, 177.936, 122.352, 224.579, 247.705]

115.778