The number of words, with or without meaning, that can be formed by taking 4 letters at a time from the letters of the word ’SYLLABUS’ such that two letters are distinct and two letters are alike, is :
Answer (integer)
240
Solution
In 'SYLLABUS' word
<br><br>1. Two S letters
<br><br>2. Two L letters
<br><br>3. One Y letter
<br><br>4. One A letter
<br><br>5. One B letter
<br><br>6. One U letter
<br><br>Number of ways we can select two alike
letters = <sup>2</sup>C<sub>1</sub>
<br><br>Then number of ways we can select two distinct
letters = <sup>5</sup>C<sub>2</sub>
<br><br>Then total arrangement of
selected letters = ${{4!} \over {2!}}$
<br><br>So total number of words, with or without meaning, that can be formed
<br><br>= <sup>2</sup>C<sub>1</sub> $\times$ <sup>5</sup>C<sub>2</sub> $\times$ ${{4!} \over {2!}}$ = 240
About this question
Subject: Mathematics · Chapter: Permutations and Combinations · Topic: Fundamental Counting Principle
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