There are 12 students in a social studies class. Three students will be selected to present their term projects today. In how many specific ways can three students be selected?

Question

anonymous · Answer

$$_{12}C_3$$ is what you are being asked for

luigi0210 · Answer

$$\frac{ 12! }{ (12-3)! }$$

anonymous · Answer

12/9?

anonymous · Answer

That's not combination.  By specific way do we mean that ORDER is important?  That decides combination or permutation.

luigi0210 · Answer

It does say specific

anonymous · Answer

A. 1,320
B. 220
C. 504
D. 36

Are my choices...

anonymous · Answer

You are on track with my thoughts Luigi.  Even if we pick random kids, they are 1st, 2nd, and 3rd in presentation.

anonymous · Answer

Combinations without Repetition
$$C(n.r) = _{n}C _{r} = \frac{ n! }{ r!(n-r)! }$$

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Permutations without Repetition
$$P(n.r) = _{n}P _{r} = \frac{ n! }{ (n-r)! }$$

anonymous · Answer

Very nice presentation some_someone!

anonymous · Answer

Oh! I see.

anonymous · Answer

12C3=220?

luigi0210 · Answer

So it is combinations..?

anonymous · Answer

yep its a combination

anonymous · Answer

That's where the 12 and 3 go, now it makes sense.

anonymous · Answer

I wish I could give medals to all of you.

anonymous · Answer

well then give it to the one who you think helped you the most :)