Aptitude - Permutation and Combination - Discussion

Discussion Forum : Permutation and Combination - General Questions (Q.No. 3)
3.
In how many different ways can the letters of the word 'CORPORATION' be arranged so that the vowels always come together?
810
1440
2880
50400
5760
Answer: Option
Explanation:

In the word 'CORPORATION', we treat the vowels OOAIO as one letter.

Thus, we have CRPRTN (OOAIO).

This has 7 (6 + 1) letters of which R occurs 2 times and the rest are different.

Number of ways arranging these letters = 7! = 2520.
2!

Now, 5 vowels in which O occurs 3 times and the rest are different, can be arranged

in 5! = 20 ways.
3!

Required number of ways = (2520 x 20) = 50400.

Video Explanation: https://youtu.be/o3fwMoB0duw

Discussion:
60 comments Page 2 of 6.

Kanakam vinay kumar said:   1 decade ago
I understood Very Clearly.

Smita said:   1 decade ago
How many ways are there to divide 5 toys among 3 children so that each child gets at least 1 toy?

Ankit said:   1 decade ago
(5!/3!) and (7!/2!) is due to the reason that in the vowels O comes 3 times therefore it has to be in the P&C part too. same case with consonants

Gaurisha said:   1 decade ago
Thanks vinod.

Abhishek said:   1 decade ago
Why we divide the vowel from all letters?and 1 more why we also calculate the vowel group also because we consider vowel as 1 and we had adjusted as a 7!. Then why again?

Shashank said:   1 decade ago
Now, let me explain in brief for those who don't find it easy.

Given word is 'CORPORATION'
Total Alphabets = 11.
vowels = 5 i:e(O,O,A,I,O)
Consonants = 11-5=6 i:e(C,R,P,R,T,N)

Now,treating vowels as 1 alphabet as asked in problm we hv=6+1=7
Also alphabet R comes twice .

Thus from "IMPORTANT FORMULAS" NO.4
For (C,R,P,T,N+(O O A I O))
p1=C(1) p2=R(2) p3=P(1) p4=T(1) p5=N(1) p6=(O O A I O)(1)

(p1+p2+p3+p4+p5+p6)= n i:e 1+2+1+1+1+1=7.

Thus,
n!/(p1!).(p2)!.....(pr!)= 7!/1!.2!.1!.1!.1!.1!=7!/2!=2520.

Similarly,
vowels (O,O,A,I,O) can be arranged in
p1=O(3) p2=A(1)p3=I(1)

p1+p2+p3 i:e= 3+1+1=5

5!/3!.1!.1!=5!/3!= 20.

Now the word 'CORPORATION' can be arranged in= 2520*20=50400 ways.

Math Wiz said:   1 decade ago
Every repeated vowels and consonants, you must divide them with the corresponding numbers if it. Like the one up there, O is repeated thrice (3 times) so you must divide them with 3!. Same goes to R which is repeated twice. That's they must be divided with 2!. After that you can just multiply both of permutation, 7! and 5! which were already divided by their repeated letters.

Sirius said:   1 decade ago
There is some flaw on the questions, it should be stated "all vowels". If not, it can mean 3 vowel together and the other 2 vowel group together but this 2 group can separate differently. Example O O_ _ _ A I O _ _ _ .

Baz said:   1 decade ago
Good day!

How did you get 2520 and 20 respectively because if u divide 7/2 and 5/3.

You will get this 3.5 and 1.7.

Belimgoe emmanuel said:   1 decade ago
How come we had 5/3 = 20ways?


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