Basic Computer Knowledge Test Questions and Answers

# Permutations Combinations

1.

In how many different number of ways 4 boys and 3 girls can sit on a bench such that girls always sit together.

A.) 720
B.) 5040
C.) 4320
D.) None of these

2.

In how many different ways can the letters of the word "CLAIM" be rearrangement?

A.) 120
B.) 125
C.) 130
D.) None of these

The total number of arrangements is
5P5  = 5! = 120

3.

If the letters of the word PLACE are arranged taken all at a time, find how many do not start with AE.

A.) 142
B.) 141
C.) 114
D.) None of these

Total no'of arrangements 5P5  = 5! = 120
no'of arrangements which do not start with AE = 120 - 6 = 114.

4.

How many arrangements of the letters of the word BEGIN can be made, without changing the place of the vowels in the word?

A.) 7 ways
B.) 6 ways
C.) 5 ways
D.) 2 ways

E,I fixed. Consonants can be arrangements in 3P3 = 3! = 6 ways

5.

If all the numbers 2, 3, 4, 5, 6, 7, 8 are arranged, find the number of arrangements in which 2, 3, 4, are together?

A.) 720
B.) 620
C.) 700
D.) None of these

If (2 3 4) is one.
we must arrange (2 3 4), 5, 6, 7, 8 in
5P5 = 5! = 120 ways
2, 3, 4 can be arranged in 3P3 = 3! = 6
120 × 6 = 720.

6.

Find 10P6

A.) 150200
B.) 151200
C.) 152200
D.) None of these

10P6 = 10!/4! = 10 × 9 × 8 × 7 × 6 × 5
= 151200.

7.

Find 9P3

A.) 414
B.) 514
C.) 504
D.) None of these

9P3 = 9!/6! = 9 × 8 × 7
= 504.

8.

Find 7P7

A.) 4440
B.) 5040
C.) 5045
D.) None of these

7P7 = 7! = 7 × 6 × 5 × 4 × 3 × 2 × 1 = 5040

9.

Find 4C2?

A.) 5
B.) 6
C.) 8
D.) 9

4C2
= 4!/(4-2)!2!
= 4!/(2! × 2!)
= (4 × 3)/2 = 6.

10.

Find 102C99?

A.) 71700
B.) 17100
C.) 17170
D.) 171700

102C99
= 102!/(102-99)!99!
= 102!/(3! × 99!)
= (102 × 101 × 100)/(3 × 2)

34 × 101 × 50 = 171700.