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.
[185.43, -65.359, -83.971, 30.359, -1.788, 181.168, 210.362, -90.041, -26.224, 239.651]