At what  rate percent per annum will a sum of Rs.20736 amount to Rs.50625 in four years, if the interest is compounded annually?

25% 

                     Principal     :      Amount

                      20736       :    50625

For four years,  

                       \(\sqrt[4]{20736 }\) :  \(\sqrt[4]{50625 }\)

                            12       :      15 

Rate % = \(\frac{3}{12}\)× 100 = 25%