At a gathering at which bankers, athletes, and lawyers are present, all of the bankers are athletes and none of the l...

Jacob on December 13, 2018

I’m happy to help. As always, let’s start with the question stem. It is a must be true question. In order to know what must be true, we have to understand the argument:

If B, A, and L ==>

B -> A (contrapositive not A -> not B)
AND
L -> not B (contrapositive B -> not L)

Remember, we know that bankers, athletes, and lawyers are all present. So there will be at least one banker, and we know from rule 1 that that banker is also an athlete. And we know from the contrapositive of rule 2 that that banker is not a lawyer. So at least one athlete is not a lawyer, which is answer C.

E is incorrect because we could hypothetically have a lawyer who is an athlete and that wouldn’t violate any of the rules or contrapositive, so “none of the lawyers are athletes” need not be true.

I hope that helps! Please let us know if you have further questions.

Zaviea on January 9, 2019

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