Multiple choice

$10$ different letters of English alphabet are given. Out of these letters, words of $5$ letters are formed. How many wards are formed when at least one letter is replaced.

  1. $69760$
  2. $98748$
  3. $96747$
  4. $97147$
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A Correct answer
Explanation

Total possible 5-letter words from 10 letters = 10^5 = 100,000. Words with no letters replaced (all distinct) = 10*9*8*7*6 = 30,240. Words with at least one letter repeated (replaced) = 100,000 - 30,240 = 69,760.

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