Question

In how many years will a sum of money double at
5% per annum simple interest?
(1) 20 years (2) 25 years
(3) 10 years (4) 15 years

Answer 1

Hey mate!!



let the initial sum be x

then,

Amount=2x (because sum will be double)

Amount = Principal + S.I
2x = x + S.I.

S.I = x

S.I = (p × r × t)/100

x = (x × 5 × t)/100

therefore, t = 20 years.

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#thankyou!!

Answer 2

Hey mate here is ur query..
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Assuming the amount (principle)=x
now total amount (principle+iñterest)=2x
so interest=x

now interest=(P*R*T)/100

AS INTEREST=X
PRINCIPLE=X
RATE=5%per annum
TIME=???

OR
x=x*5*T/100

or Time= 100/5
=20 years...
Right option is 'A'

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Hope this will help you...