Question

Find the fourth proportion to $1.4,2.6\text{and}7.2$.

• A. $13$
• B. $13.37$
• C. $12.37$
• D. $15.37$

Answer 1

The correct option is B $13.37$

Let the fourth proportion be $x$

Then, $1.4,2.6,7.2,x$ are in proportion.

Product of means $=$ Product of extremes

$\Rightarrow 2.6\times 7.2=x\times 1.4$

$\Rightarrow x\times 1.4=2.6\times 7.2$

$\Rightarrow x=\frac{2.6\times 7.2}{1.4}=13.37$

Hence , correct option is (B).