On Wednesdays, Kate usually buys some guava juice. But the only place she can buy guava juice is the local health foo...

Claire on May 27 at 04:13PM

Question

Why is the answer A instead of D? Thanks!

1 Reply

Ravi on May 27 at 04:54PM

@claire_crites,

Happy to help. Let's take a look at (A) and (D).

In looking at the argument in the stimulus, we know that it's valid.

Kate usually buys guava juice on Wednesday. If she buys guava juice,
she must get it at the local health food store. Therefore, she
sometimes shops at the health food store on Wednesdays.

Since Kate usually buys guava juice on Wednesdays, we know that she
usually goes to the store on Wednesdays. In the answer choices, we
need to find a valid argument that mirrors this argument's structure.

(D) says, "Most teachers at the Culinary Institute are allowed to use
the institute's main kitchen. Dinners at Cafe Delice are only prepared
in that kitchen. So dinners at Cafe Delice must sometimes be prepared
by Culinary Institute teachers."

The problem with (D) is that it's invalid. Based on the premises, it's
totally possible that dinners at Cafe Delice are never prepared by
Culinary Institute teachers, so this is why (D) is out.

(A) says, "Only teachers at the Culinary Institute are allowed to use
the institute's main kitchen. Most dinners at Cafe Delice are prepared
in that kitchen. So at least some dinners at Cafe Delice must be
prepared by Culinary Institute teachers."

With (A), we know that if teachers are allowed to use the main
kitchen, then the individual has to be a teacher at the institute. We
know that dinners at the cafe are often prepared in this kitchen. From
this, we know that some of the dinners at the cafe have to be made by
institute teachers. This is a valid argument that mirrors the
structure of the one in the stimulus, so it's the correct answer
choice.

Does this make sense? Let us know if you have any more questions!