of 80% in her first three exams. She then had 94% on her next exam. Celia stated that her overall mean mark was 87% because the mean of 80 a

Hello Guest,

(correction: Celia got 80% in her first three exams.)

Her reasoning is wrong because it would be right if she has written

one exam, this would be $\frac{80+94}{2}$, which is 87%, but there are three

exams and not just one. So it equals: $\frac{80+80+80+94}{4}$, which is 83.5%.

So her overall mark is no 87%, but it is 83.5%. It applies:

$\frac{Sum\ of\ values }{Number\ of\ values}$ and that is the overall mark formula.

Straight