Question 38107
A very good way to look at it is - suppose you are checking some
kind of a meter every hour and the meter shows positive for
gains and negative for losses. You just want to find an average
reading. Zero is a valid reading and must be counted.
Add the positives
4 + 2 + 6 + 5 + 3 = 20
add the negatives
-3 -3 -2 -1 -4 = -13
average = (total from readings) /(number of reading)
average = 20 -13 + 0 / 11
average = 7/11 = .636363. . .
You divide by 11, not 10,  because 0 is a valid reading, OK?