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: [172.689, -25.975, 66.37, -36.164, 217.224, 153.374, -94.201, 62.836, -52.505, 203.928]

66.758