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.

Example Input: [193.711, 110.309, -20.334, 151.607, 158.797, -97.825, -59.931]
Example Output: 62.333

Example Input: [21.953, -90.519, 92.624, 189.808, 130.57, -33.423, -16.126, 31.61, 119.582]
Example Output: 49.564

Example Input: [20.538, 100.835, -23.197, 207.707, -12.758, 152.97, 190.404]
Example Output:
90.928