Practice Questions on Permutation-Combination
Aptitude Questions and Answers

Moderate Permutation-Combination Question - 36

Q36.

In a certain laboratory, chemicals are identified by a colour-coding system. There are 20 different chemicals.

Each one is coded with either a single colour or a unique two-colour pair. If the order of colours in the pairs does not matter.

What is the minimum number of different colours needed to code all 20 chemicals with either a single colour or a unique pair of colours?

A.

$7$

B.

$6$

C.

$5$

D.

$8$

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Moderate Permutation-Combination Question - 37

Q37.

Six boxes are numbered $1,2,3,4,5$ and $6$. Each box must contain either a white ball or a black ball.

At least one box must contain a black ball and boxes containing black balls must be consecutively numbered.

Find the total number of ways of placing the balls.

A.

$15$

B.

$29$

C.

$21$

D.

$36$

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Moderate Permutation-Combination Question - 38

Q38.

In how many ways can 6 green toys and 6 red toys be arranged, such that 2 particular red toys are never together whereas 2 particular green toys are always together?

A.

11! × 2!

B.

9! × 90

C.

4 × 10!

D.

18 × 10!

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Moderate Permutation-Combination Question - 39

Q39.

There are five comics numbered from 1 to 5. In how many ways can they be arranged, so that part-1 and part-3 are never together?

A.

48

B.

72

C.

120

D.

210

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Moderate Permutation-Combination Question - 40

Q40.

The number of ways which a mixed double tennis game can be arranged amongst 9 married couples if no husband and wife play in the same is:

A.

1514

B.

1512

C.

3024

D.

3028

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