Question

A sum of money invested at 10% p.a. amounts to rupees 6500 in 3 years. What will it amount to in 2 years at 8% p.a. simple interest?​

Answer 1

let P be the principle amount

case 1

given

rate = 10% per annum

time = 3 yrs

final amount or sum = Rs. 6500

=> principle amount + simple interest = Rs.6500

=> P + (P x 10% x 3) = 6500

=> P + 0.3 P = 6500

=> 1.3 P = 6500

=> P = 6500/1.3

=> P = 5000

case 2

principle = Rs. 5000

rate = 8%

time = 2 yrs

S.I = Principle x rate x time

= 5000 x 8% x 2

= Rs. 800

final Amount or sum = Rs. ( 5000 + 800)

= Rs. 5,800

Answer 2

P+S.I= rupees 6500

=P+p×10%×3. =6500

=p+0.3 p =6500

=1.3p =6500

= p= 5000

so,P=500

R=8%

T=2year

S.I =P×R×T /100

=5000×8×2/100

=rupees 800

Amount=S.I+Principal

=rupees 800+5000

=rupees 5800