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.
One example: [1,3,5]
Solution is here: 3.000
Explanation: The mean of the input list is (1+3+5)/3, which equals 3. This is a good example.

Now, solve this: [8.159, 147.056, -47.644, -39.261, -63.989, 200.737, -77.58]
Solution:
18.211