Question

A certain sum becomes rs. 20720 in four years and rs. 24080 in six years at simple interest. Find the sum and rate of interest. A) 12000; 12% p.A. B) 14000; 12% p.A. C) 12000; 15% p.A. D) 14000; 15% p.A. 6) a certain sum becomes three times itself at simple interest in six years. It will become eight time itself in years ( _ ) 7) in how many years does a sum becomes four times itself at 25% p.A. Simple interest? A) 12 b) 15 c) 10 d) 17 8) a certain sum yields rs. 840 more interest

Answer 1

A in 4 years=20720Rs
SI=A-P

A-P=(P*R*T)/100
20720-P=(P*R*4)/100
20720-P=(P*R)/25
(25(20720-P))/P=R

A-P=(P*R*6)/100
24080-P=(P*R*3)/50
(50(24080-P))/3P=R

NOW
(25(20720-P))/P=(50(24080-P))/3P
(20720-P)=(2(24080-P))/3
62160-3P=48160-2P
14000=P