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: [161.719, 190.202, -29.327, 106.791, 116.192, 138.531, 20.151, -20.543, 28.529, -21.501]

69.074