## LGBW Grouping Setup Practice Drill Pg. 59, 2018 ed.

LSATtrainee204
LSAT Novice

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Joined: Wed Dec 19, 2018 11:07 pm
Points: 2

I am having issues with the contrapositives for question 5 in the grouping setup practice drill. The pots in the drill are really putting me through the wringer for which flowers can be inside any given pot. My issue with this question is that in the explanation on page 193 it states that if G is in then J and K are out. The contrapositive to this is that if J or K is in G is out. For question 5.1 it states that C is the answer which cannot be correct as F, H, and I are in these pots. I selected D as D stated that F, G, J, and K were in the pot. I believed this to be false as from the rules if G is in J and K are out. This doesn't make sense to me on why D would not be the correct answer choice. I feel as if I am missing something in the setup that I need clarification on.
Dave Killoran
PowerScore Staff

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Joined: Fri Mar 25, 2011 1:18 pm
Points: 3,104

LSATtrainee204 wrote: if G is in then J and K are out.

Hi Trainee,

Thanks for the question! You've run into some problems with the way the rule is stated and subsequently drawn some false inferences so let's take a closer look.

Above, I pulled the first section out of your comment that is in error. What you've stated here is a Mistaken Negation of the fourth rule. If G is out, then we do know what happens with J and K, but if G is in, then as far as J and K we do not know what happens and can make no inference. This threw off your analysis of the answers and caused the issue you had.

Let me know if that makes sense, because Mistaken Negations are one of the easiest traps of theirs to fall into (especially with rules that have negative sufficient conditions, as I discuss here: The Most Dangerous Conditional Rule on the LSAT).

Thanks!
Dave Killoran
PowerScore Test Preparation