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: [27.929, 172.413, -97.533, -21.764, 119.338, 247.986, 76.266]

74.948