In how many different ways can the letters of the word 'DETAIL' be arranged so that the vowels occupy only the odd positions?
Aptitude
Permutation and Combination
Difficulty: Medium
Choose an option
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A36
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B48
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C60
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D72
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E120
Answer
Correct Answer: 36
Explanation
Problem restatementPlace the vowels of 'DETAIL' in odd positions (1, 3, 5) and the consonants in the remaining even positions (2, 4, 6).
Given data
- Word: D, E, T, A, I, L (6 distinct letters).
- Vowels: E, A, I (3 vowels).
- Odd positions available: 1, 3, 5 (exactly 3 slots).
Concept/ApproachAssign the 3 vowels to the 3 odd slots and the 3 consonants (D, T, L) to the 3 even slots independently.
Step-by-step calculation Arrange vowels in odd slots: 3! = 6 Arrange consonants in even slots: 3! = 6 Total arrangements = 6 × 6 = 36
Verification/AlternativeBecause the counts match exactly (3 odd slots and 3 vowels), no combinations factor is needed; only permutations within positions.
Common pitfalls
- Allowing vowels in even positions or forgetting to permute consonants separately.
Final Answer36