Aptitude - Permutation and Combination - Discussion

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"No one is as deaf as the man who will not listen."

- (Proverb)

In how many different ways can the letters of the word 'LEADING' be arranged in such a way that the vowels always come together?

Answer: Option A

Explanation:

The word 'LEADING' has 7 different letters.

When the vowels EAI are always together, they can be supposed to form one letter.

Then, we have to arrange the letters LNDG (EAI).

Now, 5 (4 + 1 = 5) letters can be arranged in 5! = 120 ways.

The vowels (EAI) can be arranged among themselves in 3! = 6 ways.

Required number of ways = (120 x 6) = 720.

Shoba said: (Sat, Sep 4, 2010 06:31:36 AM)

Other than vowels there are only 4 letter then how it s possible to get 5!.

Sai said: (Fri, Sep 10, 2010 02:26:28 AM)

HI SHOBA,. 4 consonants + set of vowels (i. E. , L+N+D+G+ (EAI) ). We should arrange all these 5. So we get 5!. I think you understood.

Sachin Kumar said: (Wed, Sep 29, 2010 08:40:31 AM)

Please make me understand this answer as did not get.

Sri said: (Sun, Oct 10, 2010 09:12:07 AM)

As vowels are together take (EAI) as single letter i.e. , total no of letters are 5 (L, N, D, G, {EAI}). No of ways can arrange these 5 letters are 5! ways. Now we arranged 5 letters (L, N, D, G, {EAI}). Next we have to arrange E, A, I (they may be EAI/EIA/AEI/AIE/IAE/IEA). All these combinations imply that vowels are together. So we have to multiply 5! and 3!.

Madhusudan said: (Mon, Mar 14, 2011 10:00:52 AM)

Could you kindly let me know what is ( ! ).Howe 5! = 120 ?

Laxmikanth said: (Sat, Mar 26, 2011 11:54:29 PM)

When should we take the one or more letters as a single unit and why?

Jessie said: (Sun, Apr 10, 2011 05:47:38 AM)

7 letter word = LEADING CONDITION = VOWELS TO BE TOGETHER, HENCE (EAI) TO FOR A WORD SO NO. OF WORDS = L,(EAI),D,N,G = 5 permuation to arrange 5 letters = nPr= n!/(n-r)!=5!/0!=5! 0! is assumed to be 1!) EAI can be arranged among each other in = nPr = 3!/(3-3)= 3! hence 5! x 3! = 120 x 6 = 720

Mayur said: (Fri, Apr 15, 2011 02:30:58 AM)

How it came like nPr formula and how you have solve it? please let me know.

Bharti said: (Mon, Jul 11, 2011 06:54:15 AM)

Thanks a lot. I had confusion before your explanations. Thanks a lot.

Pavan@9966606261 said: (Fri, Aug 5, 2011 12:14:00 PM)

@mayur. You just look when ever you open the new exercise there will be availability of basic formulas. If you go through them half of the task would be finished easily. Have a good day buddy.

Siva said: (Sun, Oct 16, 2011 12:36:43 PM)

Permutations and combinations always make me to confuse much. How to decide based on the descriptive aptitude question ?

Santosh Kumar Pradhan said: (Thu, Oct 27, 2011 01:00:33 PM)

Total member 7 out of which 5 consonant and 3 vowels take 3 vowls as a 1 hen number of consonant will arrange 5! ways and these 3 vowels will arrange 3! ways though,5!*3!=720

Sagar Choudhary said: (Sun, Nov 6, 2011 07:02:12 PM)

What is this 5! and 3! ?

A.Vamsi Krishna said: (Mon, Jan 30, 2012 06:18:08 AM)

"!" this implies factorial that means a number is multiplied like for example take number 5 then its factorial will be taken as 54321 and this is equal to 120.

Raj said: (Mon, May 21, 2012 01:35:02 PM)

Friends, How do you say this question is permutation.

Mahanthesh said: (Mon, Jul 30, 2012 11:54:44 PM)

Hi guys. As per the question, it s mentioned that all vowels should be together, but it has not been mentioned that it should be EAI. According to me these 3 vowels can be arranged in 32=6 ways. And the remaining letters LDNG can be arranged in 4321= 24 ways. Can anyone explain me about this please ?

Sandeep said: (Fri, Sep 7, 2012 10:49:23 AM)

can any one explain ? y 5!*3! & y not like this 5!+3!

Srk said: (Tue, Oct 9, 2012 09:52:35 AM)

@Mahantesh. 1. There is given a word LEADING in this LDNG (consonents) , EAI (vowels). 2. They asked here vowels always come together and so we should have to take LDNG (EAI). 3. We can take as (4+1) ! i.e. here we have to take vowels as together as 1. So we have a chance of 5!. 4. But with in vowels we have many arrangements i.e 3! 5. Finally 5!*3!

Shafi said: (Thu, Oct 11, 2012 11:02:09 PM)

@Mahantesh, You are correct 3! and 4!, because you spitted vowels and consonants, But to combine them vowels+consonants. i.e. (4 consonants + 1 set of vowels) = 5! And (3 vowels {1 set}) = 3! So 5!*3! = 5x4x3x2x1x3x2x1=720.

Adhityasena said: (Sat, Feb 9, 2013 09:47:03 AM)

I get the answer to be 2720. Because, since the vowels must come together in the word LEADING, which actually has 7 letters, E and A can be taken as one unit, so now we have L, EA, D, I, N, G to be arranged and which can be done in 6! ways. But among E and A there are 2 arrangements namely EA and AE, So the final answer is 2720. Am I right !