Prep Test 78 Logic Games Solutions

By Dan Oakes.

» Please click here to open solution PDF.

I’ve re-created my thought process and diagrams as I worked through the game from Preptest 78.  These step-by-step explanations are an over-my-shoulder stream of consciousness approach, as much as memory permits.  The periodic rewriting of the diagrams shows when and how I updated my diagrams as layouts were generated, and the checklists are exactly as I created them.  As you’ll see in the sequencing games, sometimes I combine rules, but I never feel obligated to do so; I do it when I find it adds clarity, and I don’t do it when I feel it adds ambiguity or visual confusion.

Also, in the diagrams, my preference is not to note spots where certain variables can’t go.  For instance, if a rule says that X comes before Y in a sequencing game, I’m not going to clutter up my diagram by writing that Y cannot be in the first position.  Most authors and teachers recommend doing that; it’s not a right-or-wrong issue.  I’m always going over my checklist when I create layouts, and if I have an X-Y rule, I’m never going to put Y in position 1 anyway.

In the checklists, note that every time a game gives a conditional rule, I always add the contrapositive as well.  Doing so provides a second trigger to help you catch when a rule will apply.  This is certainly not the only way you could work through the games, but is just meant to share one possible way, and as I think you’ll see, it’s a way that illustrates an efficient approach, helping not only accuracy, but also timing.  I hope you find them helpful, and please feel free to contact me with any questions.

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