Tricky Combinations Question

  • Thread starter dspampi
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  • #1
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The dean of an Engineering School invites all 9 department chairpersons and their spouses to his house for a Winter Solstice party. If each department chair may attend without a spouse, but the spouse may not attend without the department chair, how many different sets of attendees are possible?

Anyone know the logic to set this answer up?
 

Answers and Replies

  • #2
Dick
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Try it for the case of 1 department chair. Now do 2. You can count those pretty easily. Now do you see how to get to 9?
 
  • #3
phinds
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Forget about the fact that there are 9 of them, for the moment, and just focus on one chair. How many ways can the chair be represented at the event?

EDIT: I see Dick beat me to it
 
  • #4
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Actually, for a precaclulus math class, that can be a pretty complex problem, since for each possible set of department chairs that can show up, their corresponding spouses may or may not necessarily show up as well.
 

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