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Quantitative Aptitude

PERMUTATION AND COMBINATION MCQs

Permutations And Combinations

Total Questions : 444 | Page 4 of 45 pages
Question 31.

Find r , if 5 4 Pr  = 6   5Pr– 1                        

  1.    3 or 5
  2.    3 or 8
  3.    5 or 4
  4.    5 or 6
 Discuss Question
Answer: Option B. -> 3 or 8
Question 32.

If    nC9   =  nP8  ,  find   n C17

  1.    1
  2.    2
  3.    3
  4.    4
 Discuss Question
Answer: Option A. -> 1
Question 33.

A committee of 3 persons is to be constituted from a group of 2 men and


3 women. In how many ways can this be done? How many of these committees would consist of 1 man and 2 women?                    

  1.    4 & 8
  2.    5 & 7
  3.    8 & 4
  4.    10 & 6
 Discuss Question
Answer: Option D. -> 10 & 6
Question 34.

What is the number of ways of choosing 4 cards from a pack of 52


          playing cards? In how many four cards are of the same suit ?           

  1.    2860
  2.    2680
  3.    2806
  4.    2608
 Discuss Question
Answer: Option A. -> 2860
Question 35.

A group consists of 4 girls and 7 boys. In how many ways can a team of


5 members be selected if the team has at least 3 girls ?                                  

  1.    71
  2.    81
  3.    91
  4.    none of these
 Discuss Question
Answer: Option C. -> 91
Question 36.

How many numbers greater than 1000000 can be formed by using the


digits 1, 2, 0, 2, 4, 2, 4?               

  1.    120
  2.    240
  3.    360
  4.    480
 Discuss Question
Answer: Option C. -> 360
Question 37.

From a group of 7 men and 6 women, five persons are to be selected to form a committee so that at least 3 men are there on the committee. In how many ways can it be done?

  1.    564
  2.    645
  3.    735
  4.    756
 Discuss Question
Answer: Option D. -> 756

We may have (3 men and 2 women) or (4 men and 1 woman) or (5 men only).


So, Required number of ways = = (7C3 x 6C2) + (7C4 x 6C1) + (7C5)


=       \(\left(\frac{7\times6\times5}{3\times2\times1}\times\frac{6\times5}{2\times1}\right)\) + (7C3 x 6C1) + (7C2)


= \(525+\left(\frac{7\times6\times5}{3\times2\times1}\times6\right)+\left(\frac{7\times6}{2\times1}\right)\)


= (525 + 210 + 21)


= 756.

Question 38.

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

  1.    360
  2.    480
  3.    720
  4.    5040
  5.    None of these
 Discuss Question
Answer: Option C. -> 720

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.


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

Question 39.

In how many different ways can the letters of the word CORPORATION be arranged so that the vowels always come together?

  1.    810
  2.    1440
  3.    2880
  4.    50400
  5.    5760
 Discuss Question
Answer: Option D. -> 50400

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 =  \(\frac{7!}{2!}=2520.\)


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


in  \(\frac{5!}{3!}=20ways.\)


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


 

Question 40.

Out of 7 consonants and 4 vowels, how many words of 3 consonants and 2 vowels can be formed?

  1.    210
  2.    1050
  3.    25200
  4.    21400
  5.    None of these
 Discuss Question
Answer: Option C. -> 25200

Number of ways of selecting (3 consonants out of 7) and (2 vowels out of 4)


= (7C3 x 4C2)


= \(\left(\frac{7\times6\times5}{4\times3\times1}\times\frac{4\times3}{2\times1}\right)\)


= 210.


Number of groups, each having 3 consonants and 2 vowels = 2


Number of ways of arranging 
5 letters among themselves   = 5!


= 5 x 4 x 3 x 2 x 1


= 120.


So,Required number of ways = (210 x 120) = 25200.

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