(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A teaching event takes two days and involves n people. Some of the

people give a talk on day 1, some others give a talk on day 2.

Everybody gives at most 1 talk, and there can be some teachers who

do not give a talk in either of the two days. At the end of the event, a few talks

are picked to be included in a book. In how many different ways can

this all happen? (there has to be at least one talk selected)

2. Relevant equations

3. The attempt at a solution

I suspect that once you have found in how many ways can you have people give talks in either of the two days (say x), you can use that a set containing x elements has 2^(x) subsets and this would be the number of possible ways to select the talks.

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# Homework Help: Combinatorics teaser (counting problem)

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