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 Rs. 5100 more. The sum is

$$\eqalign{ & {\text{Let the sum be Rs}}{\text{. }}x{\text{ and}} \cr & {\text{original rate be R}}\% \cr & {\text{Then,}} \cr & \Rightarrow \frac{{x \times \left( {{\text{R}} + 1} \right) \times 3}}{{100}} - \frac{{x \times {\text{R}} \times 3}}{{100}} = 5100 \cr & \Rightarrow 3{\text{R}}x + 3x - 3{\text{R}}x = 510000 \cr & \Rightarrow 3x = 510000 \cr & \Rightarrow x = 170000. \cr & {\text{Hence,}} \cr & {\text{Sum}} = {\text{Rs}}.170000 \cr} $$