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: [-98.008, 83.205, 68.043, -36.627, 37.526, 138.475, -48.73]

20.555