Question
Question: 10 different letters of English alphabet are given. Words of 5 letters are formed from these given l...
10 different letters of English alphabet are given. Words of 5 letters are formed from these given letters. How many words are formed when at least one letter is repeated?
A
69760
B
98748
C
96747
D
97147
Answer
69760
Explanation
Solution
No. of words with repetition = 105 = 100000
No. of words without repetition
= 10 × 9 × 8 × 7 × 6 = 30240
No. of words when atleast one letter is repeated
= 105 – 30240 = 69760