Question

10 different letters of alphabet are given words with 5 letters are formed from these given letters then the number of words which have at least one letter repeated is

Answer 1

Answer:

Number of words which have at least one letter repeated = 69760

Step-by-step explanation:

Number of letters given to form the words = 10

Number of letter words to be formed = 5

Now, we need to find the number of words which have at least one letter repeated.

$\text{So, Total number of words = }10^5$

$\text{Also, Total number of words in which no letter is repeated = }_5^{10} \txterm{P}=30240$

Now, Number of words which have at least one letter repeated = Total number of words - number of words in which no letter is repeated

= 100000 - 30240

= 69760

Hence, Number of words which have at least one letter repeated = 69760