How do you tell the difference between a permutation and a combination?

For example, if i had say 31 students in my class and i wanted to sort them into different groups and i wanted to know how many I could sort them into would that be a permutation?





Or would it be something like the different ways 5 of those students could be chosen to put problems a, b, c, d, and e on the board?





Can you explain why each would be that way in both these examples?

How do you tell the difference between a permutation and a combination?
Permutation = in how many ways can you arrange a group of objects. For example the permutations of a, b, c are:


a-b-c, a-c-b, b-a-c, b-c-a, c-a-b, c-b-a





Combination = in how many ways can you select a certain un-ordered sub-group from a larger group (e.g. select 3 students from a group of 31). For example, combination of a, b, c in groups of 2:


a%26amp;b, a%26amp;c, b%26amp;c
Reply:that would be combination





since having 1,2,3,4 is the same as 4,2,3,1. Since the kids are still in the same group, no matter how you rearrange them does not change the fact that they are still in the same group.





Permutation allows 1,2,3,4 and 4,2,3,1 but combination would be to be like 1,2,3,4 and 1,2,3,5
Reply:permutation has 2 du with order......same ppl different order r 2 possibilities





combination has nothng 2 du wit order..............same ppl different order is one possibility





permutation= a*b*c*d*e


combination= a*b*c*d*e/c*d*e
Reply:permutation means selection and arrangements of objects


combination means just selecting
Reply:Permutation = n!/(n-k)!


Combination = n!/k!(n-k)!





where n is d total number and k is the number of divisions

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