There are 6 books on a reading list.
Students must read 3 of the books on the
list. In how many different ways can a
student select 3 books?

Question

There are 6 books on a reading list. 
Students must read 3 of the books on the 
list. In how many different ways can a 
student select 3 books?

solomonzelman · Answer

6 nCr 3

calculusxy · Answer

i dont get that

solomonzelman · Answer

That means that you are choosing 6 out of 3.

calculusxy · Answer

so do i use the formula: n! / ( r!(n - r)! )

solomonzelman · Answer

Yes!

calculusxy · Answer

may  i ask. what does n and r mean?

solomonzelman · Answer

anonymous · Answer

easy you just multiply the number of books total time the required to read 6x3=18
 I think

solomonzelman · Answer

n is number you are choosing from and r is the number you are choosing.

solomonzelman · Answer

like in your case n=6 and r=3

calculusxy · Answer

18 is not on the option @Adriana101

calculusxy · Answer

thank you all!

solomonzelman · Answer

18?! No no no, this is COMBINATIONS !

solomonzelman · Answer

You welcome!