If the price of erasers goes down by 25\%, a man can buy 2 more erasers for a rupee. How many erasers are available for a rupee?
(a)2
(b)4
(c)6
(d)8
Answer
Answer (as printed): C
Explanation
Let the original price of an eraser be ₹ $x$. Reduced price $=75 \%$ of $₹ x=₹ \frac{3 x}{4}$. $$\begin{aligned} & \therefore \frac{1}{\left(\frac{3 x}{4}\right)}-\frac{1}{x}=2 \\ & \Rightarrow \frac{4}{3 x}-\frac{1}{x}=2 \Rightarrow \frac{1}{3 x}=2 \Rightarrow 6 x=1 \Rightarrow x=\frac{1}{6} . \end{aligned}$$ Hence, number of erasers available for a rupee $=6$.
Explanation as extracted from the printed page; notation may be imperfect.