Permutations of word EXTRA

CMAT 2020 · Quantitative Techniques & Data Interpretation · Easy · Permutation and Combination

In how many different ways, can the letters of the words EXTRA be arranged so that the vowels are never together ?

  1. A.

    168

  2. B.

    48

  3. C.

    120

  4. D.

    72

Answer

D

Explanation

Total arrangements of EXTRA = 5!=1205! = 120.

Vowels in EXTRA are E and A. Treating (EA) as one block, we have 4 units: X, T, R, (EA). Arrangements with vowels together = 4!×2!=24×2=484! \times 2! = 24 \times 2 = 48.

Arrangements with vowels never together = 120−48=72120 - 48 = 72.

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