English

Ten different letters of alphabet are given. Words with five letters are formed from these given letters. Then the number of words which have atleast one letter repeated is ______.

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Question

Ten different letters of alphabet are given. Words with five letters are formed from these given letters. Then the number of words which have atleast one letter repeated is ______.

Options

  • 69,760

  • 30,240

  • 99,748

  • 99,784

MCQ
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Solution

Ten different letters of alphabet are given. Words with five letters are formed from these given letters. Then the number of words which have atleast one letter repeated is 69,760.

Explanation:

Number of 5 letters words (with the condition that a letter can be repeated) = 105 = 1,00,000

Again number of words using 5 different letters is 10P5.

= 1,00,000 – 30,240 

= 69,760

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Chapter 7: Permutations and Combinations - Solved Examples [Page 120]

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NCERT Exemplar Mathematics Exemplar [English] Class 11
Chapter 7 Permutations and Combinations
Solved Examples | Q 16 | Page 120

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