Jean has 5 different colors of markers: red, blue, green, orange, and purple. Two colors are used to make a sign. How many different combinations are possible? List them.

We need to find the number of possible combinations of r objects from a set of n objects.

Jean has 5 different colors which means that n=5 and 2 colors are used to make a sign, which means r=2.

The number of combinations can be calculated with the formula:

C=n! / ((n-r) ! r!)

C=5! / (5-2) !*2!

C=5*4*3!/3!*2*1

C=20/2=10

The possible combinations are:

1. red blue

2. red green

3. red orange

4. red purple

5. blue green

6. blue orange

7. blue purple

8. green orange

9. green purple

10. orange purple