साधारण ब्याज पर 8 वर्षों में किसी राशि में 80% की वृद्धि होती है। उसी दर पर 3 वर्षों के बाद 14,000 रुपये का चक्रवृद्धि ब्याज कितना होगा?

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?