Solve the combination

Question

At a chinese buffet, there are five entree selections. If two entrees may be selected, how many ways may the plates be filled?

Answer 1

this is a combination not a permutation

it doesn't matter which entree is put in the plate first

you can choose 2 entrees from 5 entrees

use the formula n!/((r!)(n-r)!) where n=5 and r=2

5!/(2!*3!)

(5*4*3*2*1)/(2*1*3*2*1)=

(5*4)/2=

20/2

10 combinations

Answer 2

With five choices given you have five choices for the first and four choices for the second.

5 x 4 = 20 different choices.

But if this is a trick and you can choose the same entre for both it would be

5 x 5 =25 combinations. It all depends on can you choose the same entre for both.