The least number of complete years in which a sum of money put out at 20% compound interest will be more than doubled is:
3
4
5
6
Explanation:
P$ \left(1 +\dfrac{20}{100} \right)^ n $> 2P $\Rightarrow$ $ \left(\dfrac{6}{5} \right)^n $> 2. |
Now,$ \left(\dfrac{6}{5} \times\dfrac{6}{5} \times\dfrac{6}{5} \times\dfrac{6}{5} \right) $> 2. |
So, $ n $ = 4 years.