Permutation and Combination

Permutation

It is the number of different ways that a certain number of objects can be arranged in order from a large number of objects. Permutation is about arrangements.

Combination

It is the number of different ways that a certain number of objects as a group can be selected from a larger number of objects. Combination is about choice, selection and election.

Formula for Combination and Permutation:

Example 1:

There are 5 boxes, how can the boxes be arranged?

From the question itself, it tells that it is Permutation because it mentions about arrangement .So, use the permutation formula for the answer.

 P   =    n! / (n-r)!

      =   5! / (5-5)! = 5*4*3*2*1 / 2 = 120 

Example 2:

In how many ways can three student council members be elected from five candidates?

It is a combination. and the combination formula will be use for the answer.

C= n! / r!(n-r)! 

  = 5! / 3!(5-3)!=5*4*3*2*1 / 3*2*1*2*1= 20/2 =10

For deep explanation, watch the video below: