Equal count of three note types: A man has ₹480 in ₹1, ₹5, and ₹10 notes. The count of notes of each denomination is equal. What is the total number of notes he has?
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A45
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B60
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C75
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D90
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E120
Answer
Correct Answer: 90
Explanation
Introduction / Context:This is a neat arithmetic application of equal counts across denominations. The total value is a simple multiple of the sum of the denominations, scaled by the common count. We then multiply by three to get the total number of notes.
Given Data / Assumptions:
- Total money = ₹480.
- Denominations: ₹1, ₹5, ₹10.
- Let n be the equal count for each denomination.
Concept / Approach:Total value = n*(1 + 5 + 10) = 16n. Solve 16n = 480, then compute total notes = 3n. This linear setup avoids any need for trial and error.
Step-by-Step Solution:
16n = 480 ⇒ n = 480/16 = 30Total number of notes = 3n = 90Verification / Alternative check:Compute value by denomination: 30*₹1 + 30*₹5 + 30*₹10 = ₹30 + ₹150 + ₹300 = ₹480, exactly the given total.
Why Other Options Are Wrong:
- 45, 60, 75, 120: Do not correspond to 3n with n an integer satisfying 16n = 480.
Common Pitfalls:Confusing equal value with equal count, or summing denominations incorrectly (1 + 5 + 10 = 16, not 15).
Final Answer:90