The difference between compound.......?

Question

the difference between compound and simple interest on a certain sum at 15% per annum for 3 yrs is Rs. 283.50.Find the sum...

Plz answer me in detail......

the correct ans is Rs. 4000 but how?????

Answer 1

Simple Interest = PxRxT

(principal-the number) x (rate-always as a decimal....so 15% would be 0.15) x (the number of periods- so 3)

283.50 x 0.15 x 3

= 127.575

Compound Interest = P (1 + R)to power of n

.....so

283.50(1+0.15) to the power of 3 (on calculator ^3)

= 431.2