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**eillouz****Guest**

Hey!

I got another good puzzle to think about:

80 students are enrolled in 2 courses that scheduale on thursday every week in the same hours.

there are 14 weeks (14 courses)

in each week, some of the students come to course A and all the rest go to course B.

A secretery check provide something unusual:

for each 2 weeks (not necessarily consecutive weeks, but even those), exactly 40 of the students are changed their mind.

(for example: First week: 60 to A, and 20 to B. Third week: 20 to A, and 60 to B.)

The teacher of course A, ask for a list of the students that have been participate in his class for exactly 7 weeks (and so exactly 7 weeks for course B), and he got a list of 78 students (of 80 students)

i cannot show an example of the problem that meet with it.

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