Subanta
Engr2012
GMATinsight
In how many ways can the letters of word "EDUCATION" be arranged such that NO two vowels appear together?
A) 9!
B) 5!*4!
C) 5!*5!
D) 5!*4!*2!
E) 6!*4!
No 2 vowels together = the only arrangement possible will be V C V C V C V C V (with V=vowel, C=consonant). This is true as we have 5 vowels and 4 consonants and any other combination will force us to pair 2 vowels together.
Thus, the number of arrangements possible : 5 *4 *4 *3 *3 *2 *2*1 = 5!*4! ----> B is the correct answer.
We can consider the consonants as one group: the set looks like [D,C,T,N], E, U, A, I, O where the [] is regarded as one item.
Number of ways we can arrange the set = 6! (since there are 6 items)
Number of ways we can arrange [D,C,T,N] = 4!
Required arrangement = 6! * 4!
OA is EHi
SubantaYou seem to have read the question wrong. Question says that
"such that NO two vowels appear together?"EDUCATION has 5 Vowels A E I O U
and all must be separated by atleast one consonant between any two adjacent Vowels and we only have 4 consonants DCTN
i.e. in the arrangemtn A - E - I - O - U all teh dashes (-) must be occupied by atleast 1 consonant and since we have 4 places and 4 consonants so every dash (-) must have exactly one consonant.
i.e. the arrangement will be
A D E C I T O N U where all vowels
AEIOU can exchange positions among themselves in 5! ways
and similarly all Consonants
DCTN can exchange positions among themselves in 4! ways
i.e. Total Arrangements = 5!*4!
Answer: option B