A summer day is "pleasant" if there are intermittent periods of wind and the temperature stays below 84°F (29°C) all ...

Abigail on September 11, 2020

Why is B Incorrect?

Can you explain why B is wrong and how to get the correct answer?

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Shunhe on September 11, 2020

Hi @Abigail-Lee,

Thanks for the question! So this is a good question for diagramming since there’s a lot of “if-then” action. The first sentence tells us that if there intermittent wind and the temp stays below 84F all afternoon, a summer day is pleasant. We can diagram this

IW: intermittent wind

<84 & IW —> Pleasant

And then we’re told that if the temperature’s above 84 all afternoon or there’s no wind, then a summer day with high humidity levels is oppressive. This can be diagrammed

HHL: high humidity levels

(>84 v ~W) & HHL —> Oppressive

So now we have to find a weather report that conforms to this principle. Let’s take a look at (B). It tells us that the temperature was above 84, and so it was oppressive even though the humidity levels were low. But can we get that from our statements? We only know that happens if the humidity levels are high, and that’s not the case. And so as a result, we actually can’t say the day was oppressive, since we only know about summer days with high humidity levels. ??Now let’s take a look at (E), which tells us that it was windless and there was high humidity. We’ve satisfied the humidity condition and the “or” condition with the lack of wind (with “or,” we only need one condition to be right). Thus we can conclude it was an oppressive day.

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