# Tips And Tricks And Shortcuts For Combination ## Tips and Tricks and Shortcuts for Combination

We will be discussing Tips and Tricks for Combination on this page to help students to solve maximum number of Question in minimum amount of Time.

Basically there are two types of Combination Problems given below. Trick for Combination , $\mathbf{^nC_r = \frac{n!}{(n-r)! r! }}$

A combination is a mathematical technique that determines the number of possible arrangements in a collection of items where the order of the selection does not matter. ### Important tips for Combination

• Basically there are two easy tips and tricks on combination
• Repetition of digit is allowed
• Repetition of digit is not allowed
• Here, are quick and easy tips and tricks for you on. Combination problems are asked in competitive and recruitment exams.
• In combination you will learn the combination tricks and tips.

### Combination Shortcuts

• Use combinations if a problem calls for the number of ways of selecting objects and the order of selection is not to be counted.
• Summary of formula to use
OrderRepetitionFormula
CombinationYesr+n-1Cr
CombinationNonCr

### Combination Tips and Tricks and Shortcuts (with or without repetition)

Question 1(with repetition).  Jannat walks in a candy shop. She has enough money to buy 6 candies. The store has 1 pink, 1, green, and 1 white candy. How many different selections can Jannat make?

Options:

A. 480

B. 540

C. 720

D. 1540

Solution:     r + n – 1Cr = 6 + 3 – 1C6 =8C6

We know that,

$^nC_r = \frac{n!}{(n-r)! r! }$

8C6= $\frac{8!}{(8-6)! 6! }$= 28

Correct option: D

Question 2 (without repetition). In how many ways can a swimming coach select 3 swimmers from 8 swimmers?

Options:

A. 120

B. 56

C. 48

D. 24

Solution:     There are eight swimmers out of which three are to be selected

This means 8C3 = $\frac{8!}{(8-3)! 3! }$ = 56

Correct option: B