Question

11. What sum of money lent out at 5% for 3 years will produce the same interest as 900 lent out at 4% for 5 years ? 12. A sum of 1,780 becomes 2,136 in 4 years.
Find :
(i) the rate of interest.
(ii) the sum that will become 810 in 7 years at the same rate of interest.
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Answer 1

Answer:

(i)In first case, Principal (P) = Rs. 1780

Amount (A) = Rs. 2136

∴ SI = A - P = 2136 - 1780 = Rs. 356

Time(T) = 4 years

(ii) In second case, Let principal (P) = Rs. 100

Rate (R) = 5% p.a , Time (T) = 7 years

∴ Amount = P + SI = Rs. 100 + 35 = Rs. 135

If amount is Rs. 135, then principal = Rs. 100

And if the amount is Rs. 810, then principal ==Rs.600

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