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: [48.171, 203.398, 189.183, 187.558, -29.593, 147.921, 174.871, 115.694, -15.988, 70.925]

109.214