Directions: Study the following table carefully and answer the questions that follow: Number of Candidates (in lakhs) Appearing In an Entrance Examination From Six Different Cities | City | A | B | C | D | E | F | | :--- | :--- | :--- | :--- | :--- | :--- | :--- | | **Number of candidates** | 1.25 | 3.14 | 1.08 | 2.27 | 1.85 | 2.73 | Ratio of Candidates Passing And Failing Within the City | City | Ratio of Passing and Failing | | :--- | :--- | | **A** | 7 : 3 | | **B** | 5 : 3 | | **C** | 4 : 5 | | **D** | 1 : 3 | | **E** | 3 : 2 | | **F** | 7 : 5 | What is the ratio of the number of candidates failing the exam from City $D$ to that of those failing the exam from City $A$ ?
Aptitude
Statistics
Difficulty: Medium
Choose an option
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A289 : 42
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B42 : 289
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C227 : 50
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D50 : 227
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ENone of these
Answer
Correct Answer: 227 : 50
Explanation
### Concept & Strategy
To find the number of candidates failing from a specific city, multiply the total number of candidates appearing from that city by the fraction of students who failed. The failing fraction is $\frac{\text{Failing Ratio}}{\text{Total Ratio}}$. Both values are in lakhs, so we can ignore the unit when computing their ratio.
### Step-by-Step Solution
1. **Candidates failing from City D:**
- Total candidates = $2.27$ lakhs
- Passing to Failing Ratio = $1 : 3$
- Failing fraction = $\frac{3}{1 + 3} = \frac{3}{4}$
- Number of failing candidates = $2.27 \times \frac{3}{4}$
2. **Candidates failing from City A:**
- Total candidates = $1.25$ lakhs
- Passing to Failing Ratio = $7 : 3$
- Failing fraction = $\frac{3}{7 + 3} = \frac{3}{10}$
- Number of failing candidates = $1.25 \times \frac{3}{10}$
3. **Calculate the Ratio:**
- Ratio = $\frac{2.27 \times \frac{3}{4}}{1.25 \times \frac{3}{10}}$
- The $3$ in the numerators cancels out: Ratio = $\frac{\frac{2.27}{4}}{\frac{1.25}{10}}$
- Simplify the denominator: $\frac{1.25}{10} = \frac{1}{8}$
- Rewrite the expression: $\frac{2.27}{4} \times 8$
- Simplify: $2.27 \times 2 = 4.54$
4. **Convert to Ratio Format:**
- $4.54$ can be written as $\frac{454}{100}$.
- Divide both by $2$ to simplify: $\frac{227}{50}$.
- The ratio is $227 : 50$.
### Exam Strategy & Shortcut
When computing the ratio $\frac{2.27 \times \frac{3}{4}}{1.25 \times \frac{3}{10}}$, immediately cancel the common factor of $3$. You are left with $\frac{2.27}{4} \times \frac{10}{1.25}$. Notice that $\frac{10}{1.25}$ is exactly $8$. Then, $2.27 \times \frac{8}{4} = 2.27 \times 2 = 4.54$. Expressing $4.54$ as a ratio gives $454:100$, which reduces instantly to $227:50$.
### Common Pitfall
A common error is confusing the failing ratio for the passing ratio or dividing by just the failing part instead of the total ratio parts (e.g., using $\frac{3}{1}$ instead of $\frac{3}{4}$ for City D).
### Final Answer
Therefore, the correct answer is **227 : 50**.