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# 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

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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 and 94 is 87. Is Celia’s reasoning correct? Explain.

Oct 21, 2021

#1
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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

Oct 21, 2021