The simple interest on a certain sum for 3 years at 14% p.a. is 4,200 less than the simple interest on the same sum for 5 years at the same rate. Find the sum.

A. Rs. 16,000

B. Rs. 10,000

C. Rs. 15,000

D. Rs. 12,000

Answer: Option C

Solution(By Examveda Team)

$$\eqalign{ & {\text{3 years total rate}} = 14 \times 3 = 42\% \cr & {\text{5 years total rate}} = 14 \times 5 = 70\% \cr & {\text{Gap}} = 28\% \to 4200 \cr & {\text{Sum}} = \frac{{4200}}{{28}} \times 100 = {\text{Rs}}{\text{. }}15,000 \cr} $$