एक निश्चित राशि पर 2 वर्ष का साधारण ब्याज 9,600 रुपये है जबकि वार्षिक रूप से संयोजित होने वाला चक्रवृद्घि ब्याज 10,176 रुपये है। वार्षिक ब्याज दर क्या है?

A sum becomes 25 times of itself when invested for 48 years at r% simple interest per annum. Find the compound interest earned if Rs. 51,200 is invested at r% per annum when interest is compounded half-yearly, for 1.5 years.

Simple interest on a certain sum at 4% per annum for 2 years is ₹80. What is the compound interest on the same sum for the same period at the same rate?