A certain sum of money at certain rate of interest becomes rs 3420 after 2 years and at same rate after two and a half years becomes rs 3525. Find the rate percent per annum.
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Answer:
r = 70%
Step-by-step explanation:
P becomes 3,420 at 2 years and after 2.5 years it becomes 3,525
In simple interest,
An= P(1+nr/100)
Given, (i) An = 3,420 , n = 2
3,420 = P(1+2r/100)
3,420×100 = P(100+2r)
3,42,000 = P(100+2r)-----(1)
(ii) An = 3,525 ,n = 2.5
3,525 = P(1+2.5r/100)
3,525×100 = P(100+2.5r)
3,52,500 = P(100+2.5r)----(2)
(2)-(1) =>> 10,500 = 2.5pr-2pr
=>> 10,500 = 0.5pr
pr =21,000
Substitute p = 21,000/r in equation (1)
3,42,000 = 21,000/r(100+2r)
3,42,000r = 21,000(100+2r)
342r = 21(100+2r)
342r = 2,100+42r
342r-42r = 2,100
300r = 2,100
r = 70%
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