Difficulty: Medium
Correct Answer: 285120
Explanation:
Introduction / Context:
The original options suggest a fixed-position pattern for consonants and vowels rather than free intermixing. We will explicitly adopt the pattern C C C C V V V to avoid ambiguity and align with the given numeric scale.
Given Data / Assumptions:
Concept / Approach:
Number of choices for consonant block = 12P4. Number for vowel block = 4P3. Multiply blocks because they are independent under the fixed pattern.
Step-by-Step Solution:
Verification / Alternative check:
If consonants and vowels could appear in any positions (not fixed), the count would be 12C4 * 4C3 * 7!, which equals 9,979,200—far larger and inconsistent with the provided options. Hence the fixed-slot interpretation is appropriate.
Why Other Options Are Wrong:
251820, 258120, 281520 are near-misses derived from arithmetic slips or using combinations instead of permutations in one of the blocks.
Common Pitfalls:
Mixing up P and C; using 12C4 or 4C3 in place of 12P4 or 4P3 when the within-block order matters.
Final Answer:
285120
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