# Permutation and combination online test - Aptitude

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Permutation and combination having little bit difference. A permutation is nothing but the arrangement of things whereas a combination is nothing but selection of things.

In permutation, the way of arranging things is affect the result but in combination, it won’t affect anywhere.

Example for permutation: The permutation of two letters from group of three letters

AB, BA, AC, CA, BC, CB

Example for combination: The combination of two letters from group of three letters

AB, BC, CA

Formulas on Permutation & Combination:

1.  \$n!\$ = \$ 1× 2 × 3 × 4 × 5 × 6……. (n-1)× n\$

2.  \$^{n}c_{0}\$ = 1

3.  \$^{n}c_{n}\$ = 1

4.  \$^{n}P_{r}\$ = \${n!} / {(n-r)!}\$

5.  \$^{n}C_{r}\$ = \${n!} / {r!(n-r)!}\$

 Online Test - 1 (Permutation and Combination) TAKE TEST Number of questions : 20  |  Time : 30 minutes
 Online Test - 2 (Permutation and Combination) TAKE TEST Number of questions : 20  |  Time : 30 minutes

## Solved Questions Permutation and Combination

Question-1)

How many ways the letters of the word ‘ARMOUR’ can be arranged?

A) 720
B) 300
C) 640
D) 350
E) None of these

Ans: E

Solution:

Total number of letters = 6 and R is repeated twice.

Required arrangements = \$ {6!} / {2!}\$ = 360

Question-2)

How many ways the letters of the word ‘BANKING’ can be arranged?

A) 5040
B) 2540
C) 5080
D) 2520
E) None of these

Ans: D

Solution:
The total number of letters = 7 and N is repeated twice.

Required arrangements = \${7!} / {2!}\$ = 2520

Question-3)

In how many ways, a group of 3 boys and 2 girls can be formed out of a total of 4 boys and 4 girls?

A) 15
B) 16
C) 20
D) 24
E) None of these

Ans: D

Solution:

Total number of ways = (select 3 boys from group of 4 boys) × (2 girls from group of 4 girls)

\$^{4}c_{3}\$ × \$^{4}c_{2}\$ = 24