Logic Challenge #3 - Line Dancers

[alex.chasan]

Having some trouble understanding the answer that's posted to #3 on the Line Dancers game. . .for answer choice (A), it does make sense to me that P2 and N6 is impossible based on the constraints;

viz;

In any scenario, N is preceded by M, T, R, 0, and S, so the earliest it could appear is slot 6.
If P2, M1 because M - P. In this case, N is preceded by M, T, R, 0, S, AND P, (total of 6 dancers) and therefore cannot appear in slot 6.

Can anyone verify that?

My hang up, however, is that in the diagram on the answers, N is in slot 7. If that were the case, would answer choice A necessarily be false? Have I overlooked something? I'm a little confused here . . .

Thanks

[aileenann]

Hi Alex,

I think your thinking is correct. I also think you're right that there is a problem with the explanation to problem 3 on that logic game, and we'll be sure to update the problem. Thanks so much for bringing this to our attention!

It looks as though there is a typo or a slight slip in the logic as it stands. However, if you read the answer that's posted as saying that N is 6th rather than last, the rest of it holds up (of course with the diagram modified as well to show N 6th rather than 7th). This is because your explanation and Julia's rest on the same underlying logic, which can be seen on an even broader scale.

It's good practice in relative ordering games to think about which elements can go first and last. I commonly find in relative ordering games that at least for one of those slots - first or last - there are a limited number of contenders because most of the elements tend not to be floaters. Here if we look at either of the trees that can be formed according to the conditional statements, we see it's all the same as to which elements can go last. The only contenders are N and P - everything else has to have something come after it. For this reason, any answer choice that suggests that something other than N or P must go last must be false because this simply isn't possible under the current constraints. No other element can go last.

I hope that makes sense. In general, I'd recommend that you make a practice of taking 5 seconds or so after your game setup and before looking at the questions to run through this analysis on the first and last slots. It can provide helpful insights in relative ordering games as you go through the questions, and it doesn't take long to figure this out at the start.

Many thanks again for catching this error Let me know if you have any other thoughts or questions about this problem!

[noah]

My hang up, however, is that in the diagram on the answers, N is in slot 7. If that were the case, would answer choice A necessarily be false? Have I overlooked something? I'm a little confused here . . .

Thanks

So nice to know that someone reads that carefully! Alex, you're reading like a law student! Thanks, error fixed.

[ManhattanPrepLSAT1]

Here's a setup for the Line Dancers game.

[kdeclark]

A few questions:

1. Regarding the pdf. in the last posts: "S" appears multiple times in the bottom two frames. Is that intentional? Also, on the second frame, why can't P separate M and T, leaving this possibility: S M P T R O N ?

2. Regarding question 5 (the "extra challenge question"), I don't see how (D) could be true. Here's why:

We know from the setup that R is behind T and behind M. So, if R3 then M and T are next to each other (order unknown), in positions 1 and 2. However, if they are next to each other, then O must be in front of N. However, the new setup introduced by this question says that N is in front of O.

So the right answer cannot put M next to T, it seems. But if this is true, then this is a trick question! There can't be a right answer because the rules are inconsistent.

Or maybe I'm missing something?

[ManhattanPrepLSAT1]

Thanks so much for catching that - and the pdf had been downloaded 37 times and no one said anything!

I went back an looked at the frames and you are correct, the frames I posted missed the possibility that P could separate M and T, and because of this extra possibility, I don' think it's a good idea to use frames on this game.

Instead I'd set up the Tree and then notate the conditional constraints next to it. I've done this in a corrected set up and replaced the old one with the corrected version in the post above.

As to your question on #5. The Tree would would be adjusted in the following manner:

Line Dancers_Q5.pdf

(240.89 KiB) Downloaded 855 times

And with the new Tree, answer choice (D) is the only one that could be true.

We know from the setup that R is behind T and behind M. So, if R3 then M and T are next to each other (order unknown), in positions 1 and 2. However, if they are next to each other, then O must be in front of N.

Here's the issue, since O would be required to dance immediately before S, not before N.

Hope that helps and thanks for pointing out the necessary corrections!

[kdeclark]

Thanks! I see now that I was looking at the wrong rule (the O,N rather than the O,S rule).

[mia_salam]

Ok, not to be stupid, but I am new to this site. Can someone please let me know where I can find the answers for this Game? Thanks!!!

[noah]

We've set it up so that when you enter your answers, you're told whether you're right or wrong, and, I believe can request to see the right answers. Login and try (and tell me if the system isn't working).

[asdarrow]

When I click on an answer, the site does not tell me if I am correct or not on old games. Anywhere else to find all the answers to this game?

[timmydoeslsat]

When I click on an answer, the site does not tell me if I am correct or not on old games. Anywhere else to find all the answers to this game?

Like Noah said previously, I believe that once you login, answer all of the questions, and click submit at the bottom, then you will have the correct answers appear.

[noah]

When I click on an answer, the site does not tell me if I am correct or not on old games. Anywhere else to find all the answers to this game?

Like Noah said previously, I believe that once you login, answer all of the questions, and click submit at the bottom, then you will have the correct answers appear.

Thanks, Timmy.

Tech issues do arise, so shoot us an e-mail if the problem continues.

[sharp.angela.m]

RE: Question #1. I feel like I discovered a really quick way to do this question on my 4th time through. Per the constraints, every scenario will have either OS or ON. B is the only answer choice that could be correct--you don't even have to look at any of the other constraints to answer this one, right? I don't think it would normally be this way on the LSAT. They wouldn't normally knock-out four choices with one constraint (well technically two constraints put together).

[noah]

RE: Question #1. I feel like I discovered a really quick way to do this question on my 4th time through. Per the constraints, every scenario will have either OS or ON. B is the only answer choice that could be correct--you don't even have to look at any of the other constraints to answer this one, right? I don't think it would normally be this way on the LSAT. They wouldn't normally knock-out four choices with one constraint (well technically two constraints put together).

Nice catch!

You're totally right, the LSAT usually wouldn't let you off that easy!

[fyami001]

Hello,

Question regarding number 5: In the chart it seems to me like Peter is a floater, and floaters can pretty much go anywhere most of the time. So why is it that Answers A. and E. are wrong? It seems ok to put Peter in 2nd or in 6th.

P.S. Answer choice D does make sense to me.

Thanks

[ohthatpatrick]

Good question.

Peter is indeed a floater; for most of the game, P could go anywhere from 2 to 7. However, question 5 changes a rule

on us, and in doing so, it gives us two chunks we have to deal with.

When games have chunks, the chunks might make it so that floaters can't actually fit into spots where we'd otherwise

assume they can go.

The rule change for Q5 puts O and S after N, rather than before N.

This has an effect on rules 4 and 5 (tricky, but since rules 4 and 5 deal with O, S, and N, and question 5 is changing

the relationship between O, S, and N, we should investigate).

Rule 4 said that if M and T were next to each other, then we have to have OS.

This still seems possible.

However, rule 5 said that if M and T were not next to each other, then we have to have ON.

This is no longer possible. According to the new rule Q5 gives us, O comes after N.

So this sets in motion the contrapositive to rule 5:
since we can't have ON, we can't have M and T be apart (i.e.we MUST have M and T together).

If M and T are together, then rule 4 tells us that we must have OS.

So our new tree looks something like this:
(MT) -- R -- N -- OS
...............P

The "cloud" around MT is meant to indicate that they could come in either order.

Let's try (A) and see if P can be 6.

__ __ __ __ __ P __

Well, since it's so close to the last spot, we'd have to ask, "What can go last?"

It turns out nothing can go last. We can't put an OS chunk into spot 7, but everything else must come before OS.

So this answer can't work.

Similarly, for (E), let's see if P can be 2.

__ P __ __ __ __ __

Since it's so close to the first spot, we should ask, "What can go first?"

Nothing. Again, we have a chunk, the (MT) chunk, that needs to go first, but that would run into P in spot 2.

Hope this helps. Let me know if you clarification on anything.

[amandakharper]

For question 2, I don't understand why the question is D) Tori dances sometime before Peter. Why must that be true if Rafael dances 6th? I know if R is 6th then N is 7th, but beyond that, how do we know the placements of the dancers other than M must proceed P?

[stemmastery]

I am having trouble with the condition given in question 2. If R is 6th, then N must be 7th. If that happens, this breaks rules 4 and 5. One of these rules must work. So placements in the diagram must be OS or ON. It has to be one of those. What am I missing? I've looked at this question several times and have stared at in in length trying to figure out my misinterpretation.

[ohthatpatrick]

If R is 6, as you said, we know N is 7.

__ __ __ __ __ R N

This triggers the contrapositive to the last rule. Since we will NOT have ON, we know that T and M will be next to each other, which means that we must have OS.

So for the first five spots, we need (MT) and OS.
We need OS to appear before N, so OS can go anywhere in the first five spots.
And we need M - P, so we need (MT) - P

Here are the ingredients for the first five spots:
OS, (MT) - P

A) S is in front
B) OS(MT)P would be a counterexample
C) OS(MT)P would be a counterexample
D) True dat
E) OS must happen

Make sense?

[stemmastery]

Yes! Makes perfect sense. I tried the game again before looking at your explanation, and saw that I made an invalid inference before. I was requiring the (OS) to be immediately before N. I caught that, but there was still something amiss. I had made another invalid inference. I was requiring (MT) to be before (OS)... so I clearly misread my own tree diagram again.

I'm sure these two mistakes were why I had trouble with #5 before as well. This time no problem.