Test Index

Ratio and Proportion

Question : 62 of 112

Marks: +1, -0

The mean proportional between 9 and 25 is –

Solution:

Concept:

The mean proportional between two numbers is the square root of their product.

Explanation:

Let the mean proportional be

x

For two numbers

a

and

b

, the mean proportional

x

satisfies

a : x = x : b

This means

x^2 = a \times b

Here

a = 9

and

b = 25

x^2 = 9 \times 25 = 225

Taking the positive square root:

x = \sqrt{225} = 15

Thus, 15 is the mean proportional between 9 and 25.

Answer:

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