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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 |
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Answer» 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 |
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