Permutation and combination online test - Aptitude
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
Read the underneath points carefully.
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. $^{n}C_{r}$ = ${n!} / {r!(n-r)!}$
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Online Test - 1 (Permutation and Combination) TAKE TEST
Number of questions : 20 | Time : 30 minutes |
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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