Elitmus
Exam
Numerical Ability
Simple & Compound Interest
a sum of money lent out a simple interest doubled itself in 20 years. in how many years will it treble itself?
option
a)none
b)40
c)30
d)50
Read Solution (Total 6)
-
- b) 40
If Sum=x,interest rate=r,t=20 then, x*20*r/100=x , r=5
To triple the amount x*t*5/100=2x, t=40 - 11 years agoHelpfull: Yes(15) No(5)
- here sum is doubles in 20 years =>
consider sum = x and si = 2x now put values in formula we get r = 10%
now to triple the sum consider sum = x , si = 3x , r = 10% and again put values in the fromula(si = (sum*r*t)/100) we get t = 30 years
please correct me if a am wrong
answer=>b)30 - 11 years agoHelpfull: Yes(6) No(13)
- a/c, (p*r*20)/100 = 2p
=>r = 10
therfore,(p*10*t)/100 = 3p
=> t = 30 years - 11 years agoHelpfull: Yes(3) No(2)
- c)30 interest=10%
- 11 years agoHelpfull: Yes(2) No(2)
- 40
100(n-1)=rt
100/20=t
t=5
therefore t=100*2/5
=40(ans) - 11 years agoHelpfull: Yes(2) No(1)
- (n - 1) x 100 = rt
In the first part of given problem n = 2 & t = 20
Plugging values, (2 - 1) x 100 = r x 20
=> r = 5%
For the second part of problem, plug in newly obtained values of r and n = 3 :
(3 - 1) x 100 = 5 x t
t = 200/5= 40 years. - 6 years agoHelpfull: Yes(0) No(0)
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