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Ratio & Proportion · Question 28 of 67

Question 28

EasyOriginal question

What is the mean proportional between 9 and 25?

15Correct answerYour answer17Correct answerYour answer34Correct answerYour answer225Correct answerYour answer

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CorrectNot quiteAnswer A

Correct answer: A

The mean proportional of a and b is $\sqrt{ab}$ .
$\sqrt{9 \times 25} = \sqrt{225} = 15$ .

Worth noting

17 is the ordinary average of 9 and 25, and 225 is their product before taking the square root.

Concept: Mean proportional as the square root of the product
Typical timeTypical: 30 s
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The rule this testsProportion

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