Question

Ten different letters are given. Words with five letters are formed from these given letters. The number of words which have at least one letter repeated is

• A. 69760
• B. 30240
• C. 99748
• D. 43929

Answer 1

Answer: (A)

69760

Answer 2

The correct option is (A):Total number of words in which all 5 letters are repeated =$10^{5}$=100000
Total number of words in which letters are not repeated = $^{10}P_{5}$ =30240
Total number of words which has one letter repeated = $100000 - 30240$ = $69760$