Question

Ten different letters of an 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

• A. 69760
• B. 30240
• C. 99748
• D. None of these

Answer 1

Answer: (A)

69760

Answer 2

Number of words in which all the 5 letters are repeated = 10⁵ = 100000 and the number of words in which no letter is repeated are ¹⁰P₅ = 30240.

Hence the required number of ways are

100000 – 30240 = 69760.