Question

A sum of money lent on simple interest triples itself in $15$ years and $6$ months. In how many years will it be doubled?

• A. $6$ years and $3$ months
• B. $7$ years and $9$ months
• C. $8$ years and $3$ months
• D. $9$ years and $6$ months

Answer 1

The correct option is B $7$ years and $9$ months

Rs. $100$ becomes Rs. $300$ in $15$ years $6$ months.
An interest of Rs. $200$ is earned on Rs. $100$ in $15$ years, $16$ months.
An interest of Rs. $100$ is earned in $7$ years and $9$ months.
So, a sum of money doubles itself in $7$ years $9$ months.