# Math project

• Jun 10th 2006, 11:55 AM
Stuart
Math project
The coach decides that EXACTLY 2 of the 3 members of the national teem must be on the relay team. How many different relay teems of 4 athletes are possible if the order in which the athletes ski is not important?

there are 10 competitors and 3 of them are on the national teamn.
• Jun 10th 2006, 12:15 PM
Quick
Quote:

Originally Posted by Stuart
The coach decides that EXACTLY 2 of the 3 members of the national teem must be on the relay team. How many different relay teems of 4 athletes are possible if the order in which the athletes ski is not important?

there are 10 competitors and 3 of them are on the national teamn.

There are 7 non-national competitors and 2 open slots for them, so find the number of combinations for that, which is 21.
Now there are 3 national competitors and 2 open slots, the number of combinations for that is 3.
For each combination of national competitors there are 21 combinations of non-nationals, so 3*21.
3*21 is 63

so there are 63 possible relay teams.