Arithmetic Ability
Permutations and Combinations

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Q.

Nine different letters of alphabet are given, words with 5 letters are formed from these given letters. Then, how many such words can be formed which have at least one letter repeated ?

View Answer

Correct choice: A

Explanation:

Number of words with 5 letters from given 9 alphabets formed = 95 Number of words with 5 letters from given 9 alphabets formed such that no letter is repeated is = 9P5 Number of words can be formed which have at least one letter repeated = 95 − 9P5 = 59049 - 15120 = 43929
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