If both martins and harriers are in the forest, then which one of the following must be true?

Priya on December 13, 2020

Question Explanation

Can you please explain the answer to this question?

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Shunhe on January 6, 2021

Hi @priyap59,

Thanks for the question! So we’re told that both Ms and Hs are in the forest. What must then result? Well, according to rule 1, G is not in the forest. And according to the contrapositive of rule 3, since G isn’t in, W isn’t in. Now, based on rule 4, we know that at least one of J and S are in. So now we need to know something that must be true, and that’s (E), that there are at most two other kinds of birds in the forest (J and S).

Hope this helps! Feel free to ask any other questions that you might have.

Nickolas on June 15, 2021

Hi, I'm still a little confused on this question, the contrapositive of rule 3 states Not G --> Not W, but since we only know that we don't have G how can we invoke that necessary condition to mean that we don't have W as well? Wouldn't that be working backwards?

Alex on September 28, 2021

Shouldn't the question read "...that COULD be in the forest" as J&S are mutally exclusive?