Discussion
How many years will take certain amount to double at 8% interest per annum at simple interest?
Answer: B
It takes 12½ years.
An amount doubles when the simple interest equals the principal, so
\[ \begin{aligned} P &= \frac{P \times 8 \times T}{100} \\ T &= \frac{100}{8} = 12.5\ \text{years} \end{aligned} \]
A useful shortcut: at simple interest the time to double is 100 divided by the rate. 9 years is close to the 'rule of 72' for compound interest (72 / 8 = 9), which does not apply here; 13½ and 10½ years do not fit either rule.
No comment is present. Be the first to comment.
Loading…
Post your comment
Please log in or register to post a comment.
Examination Categories
- SSC Exams
- Banking Exams
- Teaching Exams
- Civil Services Exams
- Railways Exams
- Engineering Recruitment Exams
- Defence Exams
- State Government Exams
- Police Exams
- Insurance Exams
- Nursing Exams
- Other Government Exams
- NRA CET
- PG Entrance Exams
- Campus Placement
- MBA Entrance Exams
- CUET and UG Entrance
- Judiciary Exams
- Regulatory Body Exams
- Software Development