Solved

# Permutations and Combinations

Posted on 2004-04-29

Ok, Ithought I was getting the hang of this again and since I remember doing permutations in school (over 15 years ago) like the number of ways you could pick 6 numbers out of 42 to win the lottery 42*41*40*39*38*37/6*5*4*3*2*1, I thought I'd be able to handle this.

However I've been set a question which involves a group of 10 students doing a postgrad course. 4 are from business backgrounds, 4 from science and 2 from arts.

They need to select a group of 5 from the 10, so I know the number of combinations is 10*9*8*7*6/5*4*3*2*1...straight forward enough.

They then start introducing constraints into it like how many groups when each group must have 1 student from arts and 2 from business and science (question is vague...do i assume they mean 2 from each group meaning 4 in total?)

I'm not sure how to include these constraints. Any suggestions ?