Suvankar8250
In how many ways can the letters of the word "GRAPHITE" be rearranged such that the order in which the vowels appear does not change?
A. 8P3
B. 8C3 * 3!
C. 8C3
D. 8C3 * 5!
E. 8C3 * 3! * 5!
There are 3 vowels and their relative positions should stay the same (A ... I ... E) . This means there is only 1 way of arranging the 3 vowels within themselves, not 3! ways
Consider an arrangement of consonants and vowels as: GHRPAIET
There would be 3! such arrangements of consonants: GHRPAIET, GHRPAEIT, GHRPIEAT, GHRPIAET, GHRPEAIT, GHRPEIAT
But only 1 of them is acceptable GHRPAIET.
The same will be true for all arrangements. Hence total arrangements of 8 letters is 8! but it should be divided by 3! because out of every 3! cases, only 1 is acceptable. Hence answer is \(\frac{8!}{3!}\) which is the same as 8C3 * 5!
Answer (D)
Alternatively, you can think of it as replacing all vowels by V.
GRVPHVTV
Now arrange: RGVPHVTV, PHGRVVTV ... etc
The 3 Vs are just A... I...E in that order in each case and hence represent 1 arrangement only.
Hence answer will be \(\frac{8!}{3!}\) since it represents the number of ways of arranging GRVPHVTV.