Question

If $a:b=c:d=e:f=1:2$ then $(3a+5e+7e):(3b+5d+7f)$ is equal to

• A. $1:2$
• B. $1:4$
• C. $2:1$
• D. $8:7$

Answer 1

The correct option is A $1:2$

Given, $a:b=c:d=e:f=\frac{1}{2}$

$\frac{a}{b}=\frac{c}{d}=\frac{e}{f}=\frac{1}{2}$

$\Rightarrow \frac{a}{b}=\frac{1}{2}$

$a=\frac{b}{2}$

$\Rightarrow \frac{c}{d}=\frac{1}{2}$

$c=\frac{d}{2}$

$\Rightarrow \frac{e}{f}=\frac{1}{2}$

$e=\frac{f}{2}$

then, $\frac{(3a+5c+7e)}{3b+5d+7f}$

$=\frac{3\times \frac{b}{2}+5\times \frac{d}{2}+7\times \frac{f}{2}}{(3b+5d+7f)}$

$=\frac{1}{2}$