Question

In how much time will a sum become three times itself at 10% per annum simple interest??

Answer 1

There is a simple and sweet formula to solve this problem.
(n - 1) x 100 = rt
n = Number of times the amount will become in t years at r% per annum SIMPLE INTEREST.
Apply to given problem :-
n = 3, r = 10, t = ?
( 3 - 1 ) x 100 = 10 x t
t = 200/10 = 20 Years
Cheers !!!!!!
NOTE : This relation holds good only for SIMPLE INTEREST.
****** Conventional method *********
Let the number of years required = t
Let Principle = P
Amount = 3P
Interest earned = 3P - P = 2P
Now using formula SI = PRT/100, we have
2P = P x 10 x t/100
2 = 10 x t/100
t = 200/10 = 20 years

Answer 2

Answer:20 years

Step-by-step explanation:

Let sum was X and it takea t years to become 3X,means simple interest will be 3X-X=2X

So according to formula

SI=(sum×rate×time) /100

2X=(X×10×t)/100

t=20 years