A professor grades 120 research papers and reports that the average score was an 80%.What do we know about the sum of the differences of these 120 scores from their mean of 80%?
A)The sum of the differences is minimal.
B)The sum of the differences is 80%,the same as the mean.
C)The sum of the differences is equal to zero.
D)It is impossible to know without knowing each of the 120 scores.

Question

Quizplus · Accepted Answer

The sum of the differences from the mean is always equal to zero. This is a fundamental property of the arithmetic mean. Therefore, we know that the sum of the differences of these 120 scores from their mean of 80% is equal to zero.

A Professor Grades 120 Research Papers and Reports That the Average