Question

A sum of money doubles itself in 7 years. in how many years it becomes four fold?

Answer 1

I think it would take 14 years to make itself 4 times since it takes 7 to double itself.

Answer 2

In 7year money is x*2
So to get four times the money we have to double the given year ,7...
Therefore 7x2=14
Hope it helps...