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: [105.658, 66.801, 121.944, -30.101, 99.24, 209.57, 138.806, 246.768]

119.836