Question

Which expression represents the number of possible combinations of n items taken r at a time?

Answer 1

I would say the equation is

n(r)=?
 because it says taken at 1 time.

Answer 2

Answer:

$^nC_r=\frac{n!}{r!(n-r)!}$

Step-by-step explanation:

Given :Total items = n

           Items taken at a time = r

To Find: Which expression represents the number of possible combinations of n items taken r at a time?

Solution:

We will use combination over here.

$^nC_r=\frac{n!}{r!(n-r)!}$

Now Total items = n

         Items taken at a time = r

Thus expression represents the number of possible combinations of n items taken r at a time is $^nC_r=\frac{n!}{r!(n-r)!}$