Question

The least number of complete years in which a sum of money put out at 20% compound interest will be more than double, is

• A. 3 years
• B. 4 years
• C. 5 years
• D. 6 years

Answer 1

The correct option is B 4 years

$P(1+\frac{20}{100}{)}^n>2P$
or $(\frac{6}{5}{)}^n>2$
Now $(\frac{6}{5}\times \frac{6}{5}\times \frac{6}{5}\times \frac{6}{5})>2$
So $n=4$ years