The simple interest on Rs.2500 increases by Rs.700 when the time increases by 2 years. Find the rate of interest per annum.

22% 15% 5% 20%

15%

The increase in interest is due to time ⇒ \(\frac{2500\;×\;2\;×\;rate}{100}\) = 750 ⇒ rate = 15%