Question

if the interest on Rs 4800 be more than the interest on Rs 4000 by Rs 120 in 3 years at the same rate, find the rate

Answer 1

leletter principal be x
let the amount be 2x
s.i.=a-p
ans...
then rate formula

Answer 2

Part A :

⇒ S.I.=

100

P×R×T

=

100

4000×8×2

∴ S.I.=Rs.640

⇒ C.I.=P(1+

100

R

)

T

−P=8000×(1+

100

8

)

2

−8000

⇒ C.I.=8000×

25

27

×

25

27

−8000

∴ C.I.=Rs.665.6

⇒ Difference between C.I. and S.I. = Rs.665.6−Rs.640=Rs.25.6

∴ A=25.6

⇒ Part B :

⇒ Here, R=10% and C.I.−S.I.=Rs.180

⇒ S.I.=

100

P×R×T

=

100

10×P×1

∴ S.I.=

10

P

⇒ C.I.=P(1+

200

R

)

2

−P

⇒ C.I.=P×(

200

210

)

2

−P

⇒ C.I.=

400

441P

−P

∴ C.I.=

400

41P

⇒ C.I.−S.I.=

400

41P

−

10

P

=

400

P

⇒ Given difference is 180

∴

400

P

=180

∴ P=Rs.72000

∴ B=72000

⇒ 10A+B=10×25.6+72000=72256