Often students confuse between Permutations and Combinations. While both are used to find ways to do a specific job, in permutation order is important whereas in combinations, order is not important
Lets take a simple example
Question - How many 4 color stripes flags can be made using six different colors. Repetition is not allowed.
There is a proper order and there are restrictions so we will use permutation.
nPr = n!/(n-r)! = 6!/(6-4)! = 6!/2! = 6*5*4**3 = 360
Question - How many 4 color stripes flags can be made using six different colors. Repetition is allowed.
As repetition is allowed and there is no proper and restrictions, we can use combinations here
As repetition is allowed and there is no proper and restrictions, we can use combinations here
nCr = n!/r(n-r)! = 6!/
If the order doesn't matter, it is a Combination. If the order does matter it is a Permutation.
I have made a detailed video on this topic, will upload soon on YouTube.
You can practice this chapter on Testpanda.com
