Ten 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:
A. 69760
B. 30240
C. 99748
D. 42386
Answer: Option A
Solution(By Examveda Team)
Number of words which have at least one letter replaced, = Total number of words - total number of words in which no letter is repeated. = 105 – 16P5 = 100000 − 30240= 69760
This Question Belongs to Arithmetic Ability >> Permutation And Combination
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16p5 is incorrect 10p5 should be there and value of 10p5 is 30240.
Why it is not 10^5 -10p5
10^5- 10p5 is correct solution
Correct solution is 10^5- 10p5
why we have taken 16p5 and why not 10p5