An air traveler in Beijing cannot fly to Lhasa without first flying to Chengdu. Unfortunately, an air traveler in Be...

shunhe June 26, 2020

Hi @YulissaCardoza,

Thanks for the question! So first note that both what you diagrammed and what the answer choice diagrammed are logically the same thing, since Y—>G and ~G—>~Y are just contrapositives of each other, and same with G—>W and ~W—>~G. So both ways are fine!

It really comes down to how you think about the following statements in your head; whatever makes the most sense to you. So for example, the phrase “cannot reach the yellow level of achievement without first achieving the green level.” Well, there’s two ways to think about this. The first is: if you’ve achieved the yellow level, well, that must mean you achieved the green level. This would be diagrammed Y—>G, which is how you diagrammed it.

The other way of thinking about it would be, if you haven’t achieved the green level, then you haven’t achieved the yellow level. And that’s diagrammed ~G—>~Y, which is how the answer choice diagrammed it.

Next sentence is an unless: can’t achieve green unless you achieve white. Again, two ways of thinking about this. First way: if you haven’t achieved the white level, you can’t achieve the green level. That’s ~W—>~G, which is how the explanation diagrammed it.

Second way to think about that phrase: if you’ve achieved green, then you’ve also achieved white (since you can’t achieve green unless you achieve white). Well, that’s G—>W, which is how you diagrammed it. So really, it just comes down to a matter of how you personally think of these statements. But both are fine!

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

YulissaCardoza June 27, 2020

Yes that Makes total sense . I completely missed the fact that it was a contrapositive and because of that I wasn't understanding the answer choice. Thank you

shunhe June 27, 2020

Glad I could help!