Sawaal
4
Q:

In the below word how many words are there in which R and W are at the end positions?

RAINBOW

A) 120 B) 180
C) 210 D) 240

Answer:   D) 240



Explanation:

When R and W are the first and last letters of all the words then we can arrange them in 5!ways. Similarly When W and R are the first and last letters of the words then the remaining letters can be arrange in 5! ways.

Thus the total number of permutations = 2 x 5!  = 2 x 120 = 240

Subject: Permutations and Combinations
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If there are 15 dots on a circle,how many triangles can be formed?

A) 455 B) 450
C) 469 D) 500
 
Answer & Explanation Answer: A) 455

Explanation:

There are 15 dots in total,and to make a triangle we need to select any three of those dots.

 

So,15C3 = 455

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Q:

If each of the 8 teams in a league must play each other three times,how many games will be played?

A) 72 B) 84
C) 36 D) 79
 
Answer & Explanation Answer: B) 84

Explanation:

Since,each member of the league must meet every other member of the league.If they only played each other once,there would be 8C2 games.Since,each pairing of teams will occur three times,the answer will be triple.

 

Therfore, 8C2*3=84

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Q:

A polygon 7 sides.How many diagonals can be formed?

A) 14 B) 7
C) 15 D) 21
 
Answer & Explanation Answer: A) 14

Explanation:

7C2- 7 = 14

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Q:

12 people at a party shake hands once with everyone else in the room.How many handshakes took place?

A) 72 B) 66
C) 76 D) 64
 
Answer & Explanation Answer: B) 66

Explanation:

There are 12 people, so this is our n value.

 

So, 12C21= 66

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Q:

There are 7 men and 10 women on a committee selection pool.A committee consisting of President,Vice-President, and Treasurer is to be formed.How many ways can exactly two men be on the committe ?

A) 1200 B) 1240
C) 1260 D) 1620
 
Answer & Explanation Answer: C) 1260

Explanation:

There are 7C2 ways of selecting two men, and 10C1 ways of selecting a woman.Since each position in the committee is different,arrange the three people in 3! ways.

 

So, 7C2*10C1*3! =1260

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A research team of 6 people is to be formed from 10 chemists,5 politicians, 8 economists and 15 biologists.How many teams have atleast 5 chemists?

A) 7350 B) 6400
C) 6379 D) 7266
 
Answer & Explanation Answer: D) 7266

Explanation:

10C5*28C1*10C6 = 7266

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Q:

How many arrangements of the word TRIGONAL can be made if only two vowels and three consonants are used?

A) 6300 B) 3600
C) 6400 D) 7200
 
Answer & Explanation Answer: B) 3600

Explanation:

First we need to choose two vowels 3C2 and then three consonants 5C3. Now that we have 5 letters required to make the word,arrange them in 5! ways.

 

So,3C2*5C3*5! = 3600

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Q:

A student council of 5 members is to be formed from a selection pool of 6 boys and 8 girls.How many councils can have Jason on the council?

A) 715 B) 725
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Answer & Explanation Answer: A) 715

Explanation:

If Jason is on th ecouncil,this reduces the selction pool to only 13 people,out of which we still need to select 4.

 

So, 13C4 = 715

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