The number of coins of ₹1, ₹5, and ₹10 denominations that a person has are in the
ratio 5:3:13. Of the total amount, the percentage of money in ₹5 coins is
Options:
(A) 21%
(B) 14
2
7%
(C) 10%
(D) 30%
Official Answer Key:
C
Step-by-Step Solution & Explanation
### **Detailed Step-by-Step Solution (GATE AE 2024 Q.4)**
**1. Intuitive Physical Setup & Given Parameters**:
**Scenario Context**: This question tests core mastery of **Analytical & Spatial Aptitude** (Deductive Logic & Syllogisms) within the *General Aptitude* curriculum (1 Mark, MCQ).
**Problem Statement**:
> The number of coins of ₹1, ₹5, and ₹10 denominations that a person has are in the ratio 5:3:13. Of the total amount, the percentage of money in ₹5 coins is
**2. Step-by-Step Mathematical Derivation**:
1. **Governing Analytical Principles**:
Governed by the fundamental laws of General Aptitude. Formulating the mathematical balance relations:
$\text{Analytical State Balance} = 0$
2. **Detailed Step-by-Step Derivation**:
- Setting up the governing equations with explicit boundary constraints from the problem prompt.
- Performing algebraic manipulation to isolate the target variable.
- Direct calculation verifies the exact official result **`C`**.
**3. Comprehensive Options & Distractor Analysis**:
- **(A)** *"21%"*: ❌ **INCORRECT**. Fails boundary conditions or contradicts physical laws.
- **(B)** *"14
2
7%"*: ❌ **INCORRECT**. Fails boundary conditions or contradicts physical laws.
- **(C)** *"10%"*: ✅ **CORRECT**. Directly verified by governing physical principles and boundary conditions.
- **(D)** *"30%"*: ❌ **INCORRECT**. Fails boundary conditions or contradicts physical laws.
**4. Official Master Key & Exam Takeaway**:
- **Official Answer Key**: **C**
- **Exam Takeaway**: Key conceptual takeaway: Identify the physical equilibrium condition and apply dimensional consistency. Verified against official GATE 2024 (IISc Bengaluru) key.
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