Permutation and Combinations! (1 Viewer)

[shinji]

i hate permutation and combinations .. i can't seem to determine which one to use.

can anyone help me in telling me how to determine which one to use?

 

[pLuvia]

Permutations is arrangement
Combination is selection

Eg. 5 boys and 4 girls are standing in a line how many way can they be arranged if the boys and girls were to stand in alternate places

Eg. There are 5 physics, 4 maths, 3 chemistry books on a shelf how many ways can 5 of the books be selected.

etc etc

 

[Riviet]

In permutations, order is important, e.g 321 is different to 123. However, in combinations, order is irrelevant, ie 123 is the same selection as 321 and 213, etc. Look for the key words in questions and what is being chosen/arranged to help you determine which one it is.