Question

Q. If it takes a sum of money 186 months to treble itself. In how many years will it double itself?

• A. 6 years and months
• B. 7 years and 3 months
• C. 7 years 6 months
• D. 7 years 9 months
• E. none of these

Answer 1

The correct option is E none of these

For principal amount x, SI = 2x, rate of interest y
Time = 186 months $=15\frac{1}{2}$ years
SI $=2x=x\times \frac{31}{2}\times \frac{y}{100}y=\frac{400}{31}\%$
For SI = x
$x=x\times t\times \frac{400}{31}\times \frac{1}{100}$
$t=\frac{31}{4}=7\frac{3}{4}=7$ years 9 months