Permutations And Combinations Question 364

Question: The number of different words which can be formed from the letters of the word LUCKNOW when the vowels always occupy even places in

Options:

A) 120

B) 720

C) 400

D) None of these

Show Answer

Answer:

Correct Answer: B

Solution:

  • [b] In LUCKNOW, number of letters = 7 (all distinct), vowels (U, O) =2, consonants (L, C, K, N, W)=5 There are 7 letters so 7 places are required. Number of even places are 3 and vowels are 2, so 2 vowels can be placed in $ ^{3}C_2.2!=6 $ and 5 consonants can be placed in remaining places in 5! Ways. Hence, number of words $ =6.5!=720. $