Counting problem involving picking delegates

torquerotates
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Homework Statement

An organization of 100 members, 6 of whom are officers, plans to elect delegates to attend a convention. There are to be 2 delegates; one must be an officer and the other cannot be an officer. In addition, an alternate delegate, either an officer or not, will be elected and will attend if one of the regular delegates is unable to do so. How many different outcomes can this election have?

Homework Equations


The Attempt at a Solution

So, there are 6 officers to choose from and 94 non officers to choose from. If one of them are unable to be a delegate then there are 99 people to choose from(100-1 for the other person that cannot make it). So in all there should be 6*94*99=55836 different ways of picking delegates. But the back of the book gave 55272 ways. Is there something I did that was wrong?
 
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torquerotates said:

Homework Statement

An organization of 100 members, 6 of whom are officers, plans to elect delegates to attend a convention. There are to be 2 delegates; one must be an officer and the other cannot be an officer. In addition, an alternate delegate, either an officer or not, will be elected and will attend if one of the regular delegates is unable to do so. How many different outcomes can this election have?



Homework Equations





The Attempt at a Solution

So, there are 6 officers to choose from and 94 non officers to choose from. If one of them are unable to be a delegate then there are 99 people to choose from(100-1 for the other person that cannot make it). So in all there should be 6*94*99=55836 different ways of picking delegates. But the back of the book gave 55272 ways. Is there something I did that was wrong?

Two people are already out of the pool when you are choosing the third delegate...
 
Oh i see. The officer and the nonofficer that was chosen. makes sense
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...

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