# A sum of money is invested at C.I. payable annually. The interest in two successive years is 225 and 240. Find the rate of interest and original sum

2
by Ritvikrai

## Answers

2015-02-22T12:36:01+05:30

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Amount after 1 year = A  = P (1 +r/100)^1 = P (1 + r/100)
Interest = P r /100 = 225
=> P r = 22,500      --- equation 1

Amount after 2 years = B = P(1+r/100)^2  = A (1 + r/100)
Interest during 2nd year =  B - A = A r /100 = 240
A r = 24 000      -- equation 2
Hence    P (1 + r/100) r = 24 000,        now substitute Pr from equation 1
(1 + r/100 ) = 24 000 / 22 500
r /100 = 0.0667
r = 6.67 % per annum

P = 22 500 / r = Rs 3, 375

amount after 1 year = Rs 3 600
amount after 2 nd  year = Rs 3, 840

2015-02-22T22:56:16+05:30
Diff. in interest=PXR/100
15=225XR/100
R=1500/225=6.67%

PR/100=225
PR=22500
P=22500X3/20=3375

So the original sum is 3375