Principal = Rs 4000
Amount = Rs 6000
Time = 2 years
Rate = ?
Amount = principal + simple interest
Rs 6000 = Rs 4000 + simple interest
simple interest = Rs 6000 - Rs 4000 = Rs 2000
Simple interest = P*R*T/100
Rs 2000 = Rs 4000* R*2/100
R = 100/4 = 25%