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: [217.838, -75.746, 203.088, 14.891, -37.984, -65.11, 228.094]

69.296