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.
[147.702, 248.833, 214.408, 139.508, 150.178, 122.644, 239.392]