A sum of money doubles itself in 7 years. In how many years it becomes four fold?
Choose the correct choice from the following choices:
A) 35 years  B) 28 years  C) 14 years  D) 21 years  E) None of these
Double in seven years.   So 4 times will be in = 7 × (4 − 1) = 21 years.   Answer:21 years.
<result>D</result>
A sum of money doubles itself in 7 years. In how many years it becomes four fold?