Applying Combinatorics on Combinatorics

In how many ways can the letters of the word COMBINATORICS be arranged so that no 2 vowels are together?


The answer is 76204800.

This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try refreshing the page, (b) enabling javascript if it is disabled on your browser and, finally, (c) loading the non-javascript version of this page . We're sorry about the hassle.

2 solutions

Maggie Miller
Aug 14, 2015

There are 8 consanants, in which there is one repeat (C). Therefore, there are 8 ! 2 \frac{8!}{2} ways to arrange just the consanants.

There are 9 spaces between the consanants. We must choose 2 places for the O's, 2 more for the I's, and one more for the A.

Therefore, the answer is 8 ! 2 ( 9 2 ) ( 7 2 ) 5 = 76204800 \frac{8!}{2}{9\choose 2}{7\choose 2}\cdot5=\boxed{76204800} .

Nice,... difficult Qs with simple answer !! Upvoted

Syed Baqir - 5 years, 9 months ago

Log in to reply

By the way can you add few lines for beginners like here about how you created the last concrete statement , specially those parentheses.

Syed Baqir - 5 years, 9 months ago

There are 8 consonants and 5 vowels.Now the problem asks us to permute the string without putting any two or more vowels together. There will be 9 gaps created by these 8 Consonants, 5 vowels are to be placed in those 9 gaps. This can be done by (8!)* (9P5) ways, but there are duplications of C,I and O. So this whole quantity stated above has to be divided by (2!x2!x2!)=6.

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...