TASK 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.
PROBLEM: [138.63, 106.759, 86.625]

SOLUTION: 110.671

PROBLEM: [-24.857, -28.799, 240.99]

SOLUTION: 62.445

PROBLEM: [-54.497, 84.792, -83.644, 163.476]

SOLUTION:
27.532