Question

at what rate percent per annum simple interest will a sum double itself in 5 years?

Answer 1

Let principle =x
So, amount =2x
Time=5years
Rate =r
S. I=prt/100 =xr5/100
Amount = principle +s.i
2x = x+xr5/100
2x - x= xr/20
X=xr/20
R=20%

Answer 2

➡HERE IS YOUR ANSWER⬇

Let, the sum = Rs S

Given that the sum is doubled in 5 years, that means
interest (I) = Rs (2x - x) = Rs x

Time (t) = 5 years

Let, simple rate = r%

Then,

I = (S×t×r)/100

or, x = (x × 5 × r)/100

or, r = 20

Therefore, simple interest rate = 20%.

⬆HOPE THIS HELPS YOU⬅