Question

A sum of money is invested at compound interest payable annually the interest in two successive years is 225 amd 240 find rate original sum and interest earned in the third year

Answer 1

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

Answer 2

Answer:

Interest on Rs.225 for one year = Rs. 240 - Rs. 225 = Rs. 15

Rate of interest = (100 x Interest) / (P x T) = (100 x 15) / (225 x 1) = 6.67%

Interest on the original sum for one year = Rs.225

Original Sum = (100 x Interest) / R x T = (100 x 225) / (6.67 x 1) = 3375

At the end of two years, total amount = 3375 + 225 + 240 = Rs.3840

Interest for 3rd year = Interest on Rs.3840 for one year = (3840 x 6.67 x 1) / 100 = Rs. 256

Step-by-step explanation:

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