The compound interest on a certain sum of money for 2 years at 10 % per annum is Rs.420. The simple interest on the same sum at the same rate and for the same time will be_______?

A. Rs.350
B. Rs.375
C. Rs. 380
D. Rs. 400

Explanation:

The principle is P.

P(1 +10/100)² – P = 420
=> P = Rs.2000
S.I = Rs.(4000/100) = Rs.400