Question

A sum of money doubles it self in 10 years at s. i. what is the rate of interest?

Answer 1

Hey.... It is provided in the question that a sum of money doubles itself in 10 years' at SI(Simple Interest) .

We know that Simple Interest= P*T*R/100
Where P is Principal amount ,T is Time and R is Rate of interest Per annum .

If P is the amount ,it doubles itself i.e.,in 10years
So we can conclude that
(PTR)/100 = 2P
(P*10*R)/100 = 2P
5R/100=1
5R = 100
R=20.. therefore Rate of Interest is 20% Per annum..which can make a sum of money doubles itself in 10 years..