Question

on a sum of money, the compound interest calculated yearly is rs 2100 for the second year and for the third year it is rs.2205. calculate the rate of interest and the sum of money​

Answer 1

Answer:

C.I. for the third year = Rs. 1,452.

C.I. for the second year = Rs. 1,320

∴ S.I on Rs. 1,320 for one year = Rs. 1,452− Rs. 1,320= Rs. 132.

Rate of interest =

1,320

132×100

=10%.

Let the original money be Rs. P.

Amount after 2 year − amount after one year =C.I. for second year.

P(1+

100

10

)

2

−P(1+

100

10

)=1,320

P[(

100

110

)

2

−

100

110

]=1,320

⇒P[(

10

11

)

2

−

10

11

]=1,320⇒P(

100

121

−

10

11

)= Rs. 1,320

⇒P×

100

11

=Rs.1,320⇒P=

11

1,320×100

= Rs. 12,000

∴ Rate of interest =10%

and Original sum of money = Rs. 12,000