Find the number of ways to listen to 4 different CDs from a selection of 15 CDs?

Question

ganeshie8 · Answer

You can choose $4$ CDs from a collection of $15$ CDs in $\binom{15}{4}$ ways. Each of these groups of $4$ CDs can be listened in $4!$ ways, so the total number of ways to listen $4$ CDs from a collection of $15$ CDs is $\binom{15}{4}*4!$

ganeshie8 · Answer

Alternatively, you can see that 

there are $15$ choices for the first CD. 
After that, there are $14$ choices for the second CD. 
After that, there are $13$ choices for the third CD.
After that, there are $12$ choices for the fourth CD.

So, the total number of ways to listen to $4$ CDs from a collection of $15$ CDs is simply
$$15\times 14\times 13\times 12$$

anonymous · Answer

32,760?

anonymous · Answer

thank you

ganeshie8 · Answer

Looks good!

usukidoll · Answer

correct
15 x 14 x 13 x 12 = 32,760