Oct 2008 Section#17

[scharles35]

This is the question with Zacks coffeehouse.

I had choose answer(E) can you help to explain why answer choice (D) is correct.

I thought that since there are some days in where there is no poetry that means there are some days where zack doesn't offer half price coffee.

[Emily Haney-Caron]

Hi scharles,

You are confusing necessary and sufficient, here. Just because Zack schedules poetry readings on almost every Wednesday, that does not mean Wednesdays are the ONLY days he schedules readings. Similarly, just because he offers half-priced coffee on days with poetry readings, that does not mean those are the ONLY days he offers half-priced coffee. A poetry reading is sufficient for there to be half-priced coffee. It is not, however, necessary.

Zack could choose to offer half-priced coffee even on Wednesdays when there is no poetry reading. Therefore, E is wrong and D is correct - we already know that there is half-priced coffee every time there is a poetry reading, which is most Wednesdays. It is possible that it is every Wednesday, since he could also offer half-priced coffee on non-poetry reading days.