Conditional Sequencing Game Trouble - Game 4 PT55

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Conditional Sequencing Game Trouble - Game 4 PT55

Postby SaintsTheMetal » Tue May 29, 2012 5:01 am

By this I mean Advanced Linear games with rules like:
"If A is before or at the same time asX, then B is before or at the same time as Y, else B is after Y."

Doing the latest PTs leading up to the June exam, I'm running into a few games that are completely killing me. I think the best example would be Game 4 from PT55. Game 4 from PT54 also caught me up a bit, since it was the first one I've seen like this, but then PT55's seemed much harder.

Hoping someone here has some advice on how to approach Game 4 PT55.. I got to it perfectly with like 13 minutes left.. but just am totally unable to come up with the key inferences to answer the questions. The only way I've been able to struggle through it is with hardcore hypotheticals and just crunching through it, but that ate up my time and I ended up getting the last 2 wrong... need to go -0 on Games obviously

I guess I'm just not "getting it" on these games, and they're something that wasn't really in the LGB nor in the hundreds of games from the earlier PTs.. I have been able to do all other games with 0 wrong and under 8 minutes.. CDs, aisle/window bus seats, book shelves, Mannequins, whatever.. just this game...

I realized on PT54 I could draw out the 2 separate cases and link everything together.. but on the PT55 game it had the extra annoyance that the people could get off the bus at the same stop as the conditional bus stop.


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Re: Conditional Sequencing Game Trouble - Game 4 PT55

Postby timmydoeslsat » Tue May 29, 2012 1:15 pm

The fourth game at PT 55 is a unique game, but it can be made easier when you notice that the last rule is a biconditional rule.

4 stops: F L M S
4 pass: G J R V

L = 1 or 2

M ---> R still on at M


J still on at Fundy <---> G still on at Simcoe

_ 1 _
_ 2 _
_ 3 _
_ 4 _

I diagrammed the rules in exactly that manner on my paper. I needed some kind of distincion there in the last rule. If I had said J still on at F, I would have been juggling the variables about what denoted the passenger and location, etc. So this makes it easier. I also like to put a squiggly line between V and J, showing that the J doesnt have to be necessarily immediately below the V but it can be.

The last rule is biconditional, as we are told this structurally speaking:

A ---> B
~A ---> ~B

If you have been around the test for a while, you can immediately see that this is telling us that A is both sufficient and necessary for B.

I will skip question 19 since I believe you answered that in an effective manner applying the rules.

Question 20

A local question asking for what is a complete and accurate list of passengers that could get off at Mineola if that is the first stop. This is literally asking us for a laundry list of variables that can satisfy this demand.

So I know that J could not get off at this stop due to the fact that J must go off sometime after V, and with this being the first stop, it is not possible. Get rid of any answer choice with J in it. That gets rid of E. Since this is a complete and accurate list question, we are immediately drawn to answer choice (D) as it contains all of the variables mentioned by answer choices A, B, and C. I see no reason why R cannot get off at Mineola. It meets the conditions specified. Get rid of C and A. We are left with B and D. The only difference is that V is not mentioned. V's only stipulation is that it must come before J, and with this being the first spot, we have no problem with this happening. D is the answer.

Question 21

A local question asking what could be a valid hypothetical if F is the first stop. We know that if F is the first stop that L must be the second stop. So we can have a FLMS or FLSM sequence. We also know that if F is the first stop, and that J must always come after V, J will have to be on after Fundy since J cannot get off on the first stop. This triggers the condition of G still being on when Simcoe is reached. Had I not known this information I would have not diagrammed the two frames out, but since I do have this information, I know that there are inferences.

The FLMS frame would go like this:

We know that G must be last in this go around due to what we discussed above. This also forces R going off at the M spot due to our global rules. We now have the V/J rule to use and will place V and J in that order.

F 1 V
L 2 J
M 3 R
S 4 G

The second frame of FLSM can be seen like this: We know that R must be on when the bus reaches M. This means that R will be last in this frame. This now means that with S being third in this frame, that G must be on when S is reached, thus G will be 3rd. Now we place the V/J sequence to occupy the first two slots.

F 1 V
L 2 J
S 3 G
M 4 R

Answer choice D shows the second frame.

Question 22

This is directly testing our ability to think about the sequence.

We know that G is at the 2nd stop. We don't know whether this second stop is L or S, so we can show both situations.

L 1 _
S 2 G
_ 3 _
_ 4 _

S 1 _
L 2 G
_ 3 _
_ 4 _

Lets think about what must be true. Look at answer choice (C). We know that R will still be on when S is reached due to S being either 1st or 2nd.

Question 23

A local question asking what must be false when G is not at Simcoe. Well, this triggers the biconditional statement, so we know that J is not still on at Fundy. This means that J is getting off before F is reached. This means that V would also have to do that, as it comes prior to J. So no way can V still be on at Fundy if it is true that J is not on board when the bus reaches Fundy.

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Re: Conditional Sequencing Game Trouble - Game 4 PT55

Postby SaintsTheMetal » Tue May 29, 2012 6:00 pm

Thanks that is helpful.. something about this kind of question just throws me for a loop when I hit it in the test.. but thinking about it afterwards it really isn't too bad..

it took me a minute to see that the last rule was bijective but I think that is really the key to being able to handle it

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Re: Conditional Sequencing Game Trouble - Game 4 PT55

Postby lovejopd » Tue May 29, 2012 6:45 pm

Thx for an awesome explanation!!

I also had a hard time interpreting the last rule :lol:
You really have a very flexible set-up that I couldn't think of

Also the wording was truly tricky such as a person should be in the bus when shuttle van stops at X~

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