A sum of money is shared in the ratio of 3 : 4 : 5. The smallest share is divided again in the ratio of 1 : 2. What fraction of the total sum of money is the larger of the two latter shares?
Aptitude
Ratio and Proportion
Difficulty: Medium
Choose an option
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A$\frac{1}{3}$
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B$\frac{1}{6}$
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C$\frac{2}{3}$
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D$\frac{1}{12}$
Answer
Correct Answer: $\frac{1}{6}$
Explanation
### Concept & Compounding Ratios
When a fractional part of a whole is further subdivided into a new ratio, multiply the respective fractions to find the final proportion relative to the original whole.
### Step-by-Step Solution
* Let the total sum of money be divided into $3 + 4 + 5 = 12$ units.
* The smallest share corresponds to 3 units, which is $\frac{3}{12} = \frac{1}{4}$ of the total sum.
* This smallest share is now subdivided in the ratio of $1 : 2$.
* Total parts of this subdivision = $1 + 2 = 3$.
* We need to find the "larger of the two latter shares", which corresponds to 2 parts out of 3.
* This larger subdivided share is $\frac{2}{3}$ of the smallest original share.
* To find its fraction of the total sum, multiply the fractions:
$$\text{Fraction} = \frac{2}{3} \times \frac{1}{4}$$
* $\text{Fraction} = \frac{2}{12} = \frac{1}{6}$
### Exam Strategy & Shortcut
Assume a convenient total sum that is highly divisible, like ₹ 120 (since $3+4+5=12$). The shares are 30, 40, and 50. The smallest is 30. Divide 30 in the ratio $1 : 2$, giving parts of 10 and 20. The larger part is 20. The fraction of the total is $\frac{20}{120} = \frac{1}{6}$.
### Common Pitfall
Finding the fraction of the smallest share ($\frac{2}{3}$) but forgetting to multiply it by the initial ratio fraction ($\frac{1}{4}$) to find the proportion relative to the *total* sum.
### Final Answer
Therefore, the correct answer is **$\frac{1}{6}$**.