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

• total words = 10^5 = 100000
  words with no letter repeat = 10*9*8*7*6 = 30240
  
  hence words with one repeat = total - none
  =100000-30240
  =69760
• 9 years agoHelpfull: Yes(4) No(0)
• WE can do it easily
  
  1st of all find five letter word with repetition ,will be 10*10*10*10*10=10^5
  
  then find five letter word without repetition=10*9*8*7*6 OR 10P5
  
  then subtract them...
  
  10*10*10*10*10-(10*9*8*7*6)=69760
• 8 years agoHelpfull: Yes(1) No(0)
• can u please give the solution of this problem
  
• 10 years agoHelpfull: Yes(0) No(0)
• 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
• 8 years agoHelpfull: Yes(0) No(0)