Subject: General Aptitude · Chapter: Ratio and Proportion · Exam: · Marks: · Difficulty:
Three numbers $A, B$ and $C$ are in the ratio 1 : 2 : 3. Their average is 600. If $A$ is increased by 10\% and $B$ is decreased by 20\%, then to get the average increased by 5\%, $C$ will be increased by
(a)90
(b)100
(c)150
(d)180
Answer
Answer (as printed): D
Explanation
Let $A=x, B=2 x, C=3 x$. Then, $\frac{x+2 x+3 x}{3}=600$ $$\Rightarrow 2 x=600 \Rightarrow x=300 .$$ So, $A=300, B=600, C=900$. New value of $A=110 \%$ of $300=330$. New value of $B=80 \%$ of $600=480$. New average $=105 \%$ of $600=630$. New value of $C=(630 \times 3)-(330+480)=1080$. $$\text { ∴ Increase in value of } C=(1080-900)=180 .$$
Explanation as extracted from the printed page; notation may be imperfect.