ABC26GN3006 · Ratio and Proportion
Subject: General Aptitude · Chapter: Ratio and Proportion · Exam: · Marks: · Difficulty:
If $a: b=2: 5$, then the value of $(2 a+3 b):(7 a+$ 5b) is
(a)19 : 31
(b)19 : 39
(c)31 : 19
(d)99 : 13
Answer
Explanation
$$\begin{aligned} & \frac{a}{b}=\frac{2}{5} \Rightarrow \frac{2 a+3 b}{7 a+5 b}=\frac{2\left(\frac{a}{b}\right)+3}{7\left(\frac{a}{b}\right)+5}=\frac{2 \times \frac{2}{5}+3}{7 \times \frac{2}{5}+5}=\frac{19}{5} \times \frac{5}{39}=\frac{19}{39} \\ & \Rightarrow(2 a+3 b):(7 a+5 b)=19: 39 \end{aligned}$$
Explanation as extracted from the printed page; notation may be imperfect.
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