Question:

Let \(S\) be the set of all words formed by arranging all the letters of the word HOMOGENEOUS. If a word is randomly chosen from the set \(S\), then the probability that the word selected has all the consonants together is

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When several letters must stay together, treat them as a single block first. Arrange the block with the remaining letters and then multiply by the internal arrangements of the letters within the block.
Updated On: Jul 29, 2026
  • \(\dfrac{6!\,6!}{11!}\)
  • \(\dfrac{7!\,5!}{11!}\)
  • \(\dfrac{6!\,5!}{11!}\)
  • \(\dfrac{8!\,5!}{11!}\)
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The Correct Option is B

Solution and Explanation

Concept: Probability \[ = \frac{\text{Number of favourable arrangements}} {\text{Total number of arrangements}}. \] When all consonants are together, treat them as a single block and then arrange the resulting objects.

Step 1: Find the total number of arrangements of HOMOGENEOUS. The word HOMOGENEOUS contains \(11\) letters. The repeated letters are \[ O,O,O \] and \[ E,E. \] Hence, \[ n(S) = \frac{11!}{3!\,2!}. \]

Step 2: Identify vowels and consonants. Vowels: \[ O,O,O,E,E,U \] which are \(6\) letters. Consonants: \[ H,M,G,N,S \] which are \(5\) distinct letters.

Step 3: Count arrangements with all consonants together. Treat the \(5\) consonants as one block. Then we have \[ 1+6=7 \] objects: \[ [\text{Consonant Block}],\;O,\;O,\;O,\;E,\;E,\;U. \] These can be arranged in \[ \frac{7!}{3!\,2!} \] ways. The consonants inside the block can be arranged in \[ 5! \] ways. Therefore, \[ \text{Favourable arrangements} = \frac{7!}{3!\,2!}\times 5!. \]

Step 4: Calculate the probability. \[ P = \frac{\frac{7!}{3!\,2!}\times 5!} {\frac{11!}{3!\,2!}}. \] \[ = \frac{7!\,5!}{11!}. \] Therefore, \[ \boxed{\frac{7!\,5!}{11!}} \] \[ \boxed{\text{Answer = (B)}} \]
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