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

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 |

**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