A sum was put at simple interest at a certain rate for 3 years. Had it been put at 1\% higher rate, it would have fetched ₹ 5100 more. The sum is
(a)₹ 1,20,000
(b)₹ 1,25,000
(c)₹ 1,50,000
(d)₹ 1,70,000
Answer
Answer (as printed): D
Explanation
Let the sum be ₹ $x$ and original rate be $R \%$. Then, $\frac{x \times(R+1) \times 3}{100}-\frac{x \times R \times 3}{100}=5100$ $$\begin{aligned} & \Rightarrow \quad 3 R x+3 x-3 R x=510000 \\ & \Rightarrow \quad 3 x=510000 \Rightarrow x=170000 . \end{aligned}$$ Hence, sum $=₹ 170000$.
Explanation as extracted from the printed page; notation may be imperfect.