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NDA Mathematics Permutation Combination 2025 NDA 2025 (Phase 1)

NDA Mathematics Question (2025) — Solution

Question

How many 7-letter words (with or without meaning) can be constructed using all the letters of the word CAPITAL so that all consonants come together in each word?

Options

  1. A. 360
  2. B. 300
  3. C. 288
  4. D. 240

Answer

C. 288

Step-by-step solution

The word CAPITAL has 7 letters. Vowels: A, I, A (3 letters, where A is repeated twice) Consonants: C, P, T, L (4 distinct letters) Since all consonants must come together, they are treated as a single unit: (C, P, T, L). Now, there are 4 units to arrange: the consonant group and the 3 vowels (A, I, A). The number of ways to arrange these 4 units is 4! 2! because the letter A appears twice. 4! 2! = 12 The 4 consonants can be arranged among themselves in 4! ways. 4! = 24 Total number of words = 12 24 = 288 Answer: 288

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