The compound interest on a certain some for 2 successive years are Rs. 225 and Rs. 238.50. The rate of interest per annum is = ?

Explanation:-

$$\eqalign{ & {\text{Required rate }}\% \cr & {\text{ = }}\frac{{\left( {238.50 - 225} \right)}}{{225}} \times 100 \cr & = 6\,\% \cr}$$