Medium INTEGER +4 / -1 PYQ · JEE Mains 2020

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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