Let's assume SI = K P = 20K T = 1 R = ?
SI = P . R . T /100 R = P . T / SI . 100 R = 20K.1/K.100
or R = 5%
A sum was invested for 3 years at simple interest at a certain rate, had it been invested at 4% higher rate of interest, it would have fetched Rs 600 more. What was the sum invested?