Tips And Tricks And Shortcuts For Combination

Tips & Tricks and Shortcuts for Combination

  • Basically there are two easy tips and tricks on combination
    (i) Repetition of digit is allowed
    (ii) 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.
tips and tricks and shortcuts on combination

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,

nCr= n!/(r!) (n-r)!

8C6= 8!/6! (8 – 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 = 8!/3! (8-3)! = 56

Correct option: B

Please Login/Signup to comment