Tips And Tricks And Shortcuts For Combination

Tips And Tricks And Shortcuts Of Combination

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

Tips And Tricks And Shortcuts Of Combination

Tips & Tricks and Shortcuts 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 Tips and Tricks and 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

Read Also – How to solve Combination Question Quickly.