Consider the following statements If a sum of money is lent at simple interest, then the 1. money gets doubled in 5 years if the rate of interest is $16\\frac{2}{3}$% 2. money gets doubled in 5 years if the rate of interest is 20%. 3. money becomes four times in 10 years if it gets doubled in 5 years. Of these statements,
Aptitude
Simple Interest
Difficulty: Medium
Choose an option
-
A1 and 3 are correct
-
B2 alone is correct
-
C3 alone is correct
-
D2 and 3 are correct
Answer
Correct Answer: 2 alone is correct
Explanation
### Concept & Simple Interest
Let's evaluate each statement individually using simple interest formulas.
For a sum to double, $S.I. = P$.
For a sum to become four times, $S.I. = 3P$.
### Step-by-Step Solution
* **Statement 1:**
Sum doubles $\Rightarrow S.I. = P$. Time = 5 years.
Rate $= \frac{100 \times S.I.}{P \times T} = \frac{100 \times P}{P \times 5} = 20$%.
Statement 1 says rate is $16\frac{2}{3}$%, so it is **False**.
* **Statement 2:**
Sum doubles in 5 years. As calculated above, Rate = 20%.
Statement 2 says rate is 20%, so it is **True**.
* **Statement 3:**
Sum doubles in 5 years $\Rightarrow S.I. = P$ in 5 years.
To become 4 times, $S.I. = 3P$.
Time required $= 3 \times 5 = 15$ years.
Statement 3 says 10 years, so it is **False**.
### Exam Strategy & Shortcut
Verify each statement quickly.
1. $R = 100/5 = 20 \neq 16.66$. (False)
2. $R = 100/5 = 20$. (True)
3. If $SI = P$ in 5 yrs, then $SI = 3P$ in $3 \times 5 = 15$ yrs. (False)
Only statement 2 is correct.
### Common Pitfall
In statement 3, thinking that if it doubles in 5 years, it becomes 4 times in 10 years by applying compound interest logic. For simple interest, the interest grows linearly, not exponentially.
### Final Answer
Therefore, the correct answer is **2 alone is correct**.