<p>Can someone please explain to me how to do this?
"From a gorup of 6 juniors and 8 seniors who make up student council, 2 juniors and 4 seniors will be chosen to make up a 6-person committee. How many different 6-person committees are possible?"</p>
<p>Thanks</p>
<p>(6<em>5)(8</em>7<em>6</em>5)
6 possibilities for the first junior, 5 for the next
same thing for the seniors
I think this is correct</p>
<p>yeah thats what i thought but it's not correct... the answer should be 1,050 but i dont know how to do it</p>
<p>It's pretty facile:
(6!/(2!(6-2)!))x(8!/(4!(8-4)!)=1050
15x70=1050</p>
<p>You must understand the rules for permutations and combinations.</p>
<p>Combinations:
n!/(r!(n-r)!) where n is the number of items in the primary set and r the number in the subset.</p>
<p>Permutations:
n!/(n-r)!</p>
<p>how would i enter that into the calculator? because i have no idea wat the "!" means</p>
<p>haha nevermind got it its the nCr function in the calculator</p>
<p>! means factorial. That is to say: 6!=6<em>5</em>4<em>3</em>2</p>
<p>you could also quickly jot out the possibilities, or a ratio of the possibilities (and multiply accordingly). this is what I often end up doing when I don't want to mess up a factorial.</p>