# 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

1.  7

2.  6

3.  5

4.  8

4

6

Explanation :
No Explanation available for this question

# 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.

1.  15

2.  20

3.  21

4.  36

4

21

Explanation :
No Explanation available for this question

# 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

1.  11! × 2!

2.  9! × 90

3.  4 × 10!

4.  18 × 10!

4

18 × 10!

Explanation :
No Explanation available for this question

# 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:

1.  1514

2.  1512

3.  3024

4.  3028

4

1512

Explanation :
No Explanation available for this question

# Ten coins are tossed simultaneously. In how many of the outcomes will the third coin turn up a head

1.  210

2.  29

3.  3×28

4.  None of these

4

29

Explanation :
No Explanation available for this question

# There are 5 Rock songs, 6 Carnatic songs and 3 Indi pop songs. How many different albums can be formed using the above repertoire if the albums should contain at least 1 Rock song and 1 Carnatic song

1.  15624

2.  16384

3.  6144

4.  240

4

15624

Explanation :
No Explanation available for this question

# A book-shelf can accommodate 6 books from left to right. If 10 identical books on each of the languages A,B,C and D are available, In how many ways can the book shelf be filled such that book on the same languages are not put adjacently

1.  40P6 / 6!

2.  10×95

3.  6P4 / 2!

4.  4×35

4

4×35

Explanation :
No Explanation available for this question

# In how many ways can the letters of the word ABACUS be rearranged such that the vowels always appear together

1.

2.  3!×3!

3.

4.

5.

5

Explanation :
No Explanation available for this question

# If the letters of the word SACHIN are arranged in all possible ways and these words are written out as in dictionary, then the word ‘SACHIN’ appears at serial number:

1.  601

2.  600

3.  603

4.  602

4

601

Explanation :
No Explanation available for this question

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