Advanced Linear Setup Practice Drill #2

[sarahrperdue]

Hi! I am working in the workbook and have a question. Advanced linear setup practice drill #2 on page 46....
The explanation is on page 168. I have it set up properly with L/N in the fourth spot, but I'm having trouble understanding something. The book says, "because s is female, and L AND N are female, the four males must be K O P & R.
Why are we deducing that both L AND N are female? If L is in spot4, nothing is stoping N from being in spot 3, or even 7.... Which would make N male.

According to the logic in the book, this restricts L/N to spots 4, 2, and 6 (leaving S in either 2 or 6. And that seems like an inference that is incorrect. Please help me understand!

Thanks!

[Jon Denning]

Hey Sarah,

Thanks for the question! For this drill, we're given the construct that the four males cannot be in consecutive positions, meaning they must be positioned in 1, 3, 5, and 7. That means that the runners who could possibly fill 2, 4, and 6 must be female.

So when you see a rule stating that either L or N is 4th, the implication (the inference) is that because 4th is a female and L and N are potentially in that place, they must both be females. That is, being told that they could both fill that position means that they must both be females.

And that's an important consideration for the LSAT: if they tell you that something is possible (with a rule or scenario or local question) you can trust that it is, in fact, possible, and the facts that make it so can be trusted.

Note: this isn't quite the same thing as a rule saying something like, "Mary works on either Monday or Tuesday," where it could be the case that you can determine she must work Tuesday only. In this drill we're dealing with an unchanging characteristic of the variables themselves—male or female—so there's no ambiguity about changes with L and N: if they can both go fourth they're both females, even if you can determine that only one of them ever does go fourth.

I hope that helps to explain it. It's a little tricky but it does get tested, so I'm glad you noticed and brought it up!