professor must randomly select 4 students to participate in a mock debate. There are 18 students in his class. In how many diffe
1 answer:
You might be interested in
<h3>Answer: 120 different ways</h3>
=======================================================
Explanation:
There are...
- 6 ways to select the first place winner
- 5 ways to pick the second place winner
- 4 ways to pick the third place winner
We start with 6, and count down by 1 each time we fill up a slot. We stop once the third slot is filled or accounted for. The countdown is to ensure that we don't pick the same person twice. From here, multiply those values: 6*5*4 = 30*4 = 120
Interestingly, this is equal to 5! = 5*4*3*2*1 = 120 because the 3*2 becomes 6 and that *1 at the end doesn't affect things. Though usually results of permutation problems don't always end up like this. The order matters because a result like ABC is different from BAC, where A,B,C,D,E,F are the six school organizations.
As a slightly longer way to do the problem, you can use the nPr formula which is where n = 6 and r = 3 in this case. The exclamation marks indicate factorial. If you go this route, you should find that one of the steps will involve 6*5*4.