Sufficient & Necessary Questions - - Question 7

If the city council maintains spending at the same level as this year's, it can be expected to levy a sales tax of 2 ...

MariaTokarev December 23, 2020

Don’t understand the answer

Can someone explain the answer C (the correct answer)? I didn’t really get how it works.

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shunhe December 29, 2020

Hi @MariaTokarev,

Thanks for the question! So we should first diagram this stimulus, which will help us more with figuring out what parallels the reasoning best. We diagram this stimulus

Maintain spending —> 2% sales tax
Conclusion: Higher tax —> Higher expenditures

So this is a flawed question. The second statement is supposed to be a contrapositive of the first. So this is supposed to be

~2% sales tax —> ~Maintain spending

But it’s not necessarily the case that not having a higher sales tax means a 2% sales tax, or that not maintaining spending means higher expenditures. So we want an answer choice that also takes the contrapositive but replaces terms in a weird way. And so that’s what (C) does. We diagram it

~Increase wages —> Prices stay the same
What the contrapositive is supposed to be: ~Prices stay the same —> Increase wages
What the contrapositive actually is: Increase prices —> Increase wages

And we can see that prices not staying the same and increased prices aren’t the same thing, since the prices could also go down.

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