Question: The number of words which can be made out of the letters of the word MOBILE when consonants always occupy odd places is [RPET 1999]
Options:
A) 20
B) 36
C) 30
D) 720
Show Answer
Answer:
Correct Answer: B
Solution:
- The word MOBILE has three even places and three odd places. It has 3 consonants and 3 vowels. In three odd places we have to fix up 3 consonants which can be done in $ {}^{3}P_3 $ ways. Now, remaining three places we have to fix up remaining three places we have to fix up remaining three which can be done in $ {}^{3}P_3 $ ways. The total number of ways $ ={}^{3}P_3\times {}^{3}P_3 $ = 36.