Test Index

Ratio and Proportion

© examsnet.com

Question : 90 of 112

Marks: +1, -0

If b be the mean proportional between a & c then

$b \times b = ac$
$b = \frac{a + c}{2}$
$b = a + c$
$b = \frac{a - c}{2}$

Solution:

Concept:

The mean proportional between two numbers

a

and

c

is the geometric mean, which satisfies

b^2 = a c

.

Explanation:

By definition, if

b

is the mean proportional between

a

and

c

, then

\frac{a}{b} = \frac{b}{c}

.

Cross-multiplying gives

b \times b = a \times c

.

This is equivalent to

b^2 = a c

.

Answer:

b \times b = a c

(i.e.,

b^2 = a c

).

© examsnet.com

Go to Question:

Prev Question

Next Question