ABC26GN3028 · Ratio and Proportion
Subject: General Aptitude · Chapter: Ratio and Proportion · Exam: · Marks: · Difficulty:
If $a: b=c: d=e: f=1: 2$, then $(3 a+5 c+7 e):$ $(3 b+5 d+7 f)$ is equal to
(a)1 : 2
(b)1 : 4
(c)2 : 1
(d)8 : 7
Answer
Explanation
$\frac{a}{b}=\frac{c}{d}=\frac{e}{f}=\frac{1}{2} \Rightarrow b=2 a, d=2 c, f=2 e$. $$\begin{aligned} \frac{3 a+5 c+7 e}{3 b+5 d+7 f} & =\frac{3 a+5 c+7 e}{3 \times 2 a+5 \times 2 c+7 \times 2 e} \\ & =\frac{3 a+5 c+7 e}{2(3 a+5 c+7 e)}=\frac{1}{2} \end{aligned}$$
Explanation as extracted from the printed page; notation may be imperfect.
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