PT 34, S4 (games), Q21 (and other questions like it)

sea change
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Joined: Thu Mar 24, 2011 8:57 am

PT 34, S4 (games), Q21 (and other questions like it)

Postby sea change » Sat Mar 26, 2011 3:16 pm

I wonder if someone could suggest or point me to some source that suggests a specific process for dealing with with this type of question, i.e. in/out games where you're asked for the minimum or maximum number of elements that could conceivably go in this or that group.

I inevitably end up winging it on these things, which in general does not work out all that well. I'll start with, okay, what if they're all in group X? Most times it's obvious this can't be the case. After that I'm not sure how to proceed and just end up sort of randomly placing variables here and there in a totally nonsystematic fashion and seeing what happens. Time passes; perhaps I've somehow managed to eliminate an answer or two, but I'm still just aimlessly futzing around with various scenarios. I freak out and guess. The end.

Thanks.

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EarlCat
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Re: PT 34, S4 (games), Q21 (and other questions like it)

Postby EarlCat » Sat Mar 26, 2011 5:09 pm

sea change wrote:I wonder if someone could suggest or point me to some source that suggests a specific process for dealing with with this type of question, i.e. in/out games where you're asked for the minimum or maximum number of elements that could conceivably go in this or that group.

I inevitably end up winging it on these things, which in general does not work out all that well. I'll start with, okay, what if they're all in group X? Most times it's obvious this can't be the case. After that I'm not sure how to proceed and just end up sort of randomly placing variables here and there in a totally nonsystematic fashion and seeing what happens. Time passes; perhaps I've somehow managed to eliminate an answer or two, but I'm still just aimlessly futzing around with various scenarios. I freak out and guess. The end.

Thanks.


Whenever I have a group game with only two places to put my elements, I work it as an in/out game. In this game we are grouping doctors into clinics S and R. I picked S to be "in" and R to be "out." (It doesn't really matter which is which as long as you're consistent.) An "in" element will be designated in my conditionals by its name alone, e.g. "J," and an "out" element will be negated, e.g. ~J.

The rules then form conditionals. For instance, the first rule looks like this:
J --> ~K
K --> ~J

In an in/out game, whenever you have a rule like this with a negative on one side and a positive on the other, the side of the conditional with the negative (~) indicates that an element MUST be placed on that side of the IN/OUT diagram.

In other words, if I draw a T chart for my game, either J or K must fill a slot on the "out" side.

IN (S) | OUT (R)
------- |---------
........| J/K (ignore the dots, they're just for spacing)

The second rule gives me a similar deduction:

~J --> O
~O --> J

IN (S) | OUT (R)
-------|---------
O/J ..| J/K


As you worth through the rules in this game, you can make 4 of these deductions (it looks like you can make more, but once an element, like L, is used to make a slot, it can't be used again to make a slot on the same side). Thus, at least 2 doctors must be at S ("in") and two must be at R ("out"). Now you know, without considering any other info, that at least two doctors, but not more than four will be at S.

Immediately you can cross off zero and one as the minimum number of doctors that can be at S.

Now the question is whether it's actually possible to leave only two doctors at S. This requires revisiting the rules. For instance, when O is "in," N is "in." But you also have an "in" slot that must be filled by either P or K, so that makes a minimum of 3 doctors when O is "in." No good. Putting O and N "out" puts J and P "in," which, in turn, put K and L "out." Bingo. We have successfully put only two doctors at S. The minimum number of doctors at Souderton is two.
Last edited by EarlCat on Fri Apr 01, 2011 4:43 pm, edited 3 times in total.

SanDiegoJake
Posts: 149
Joined: Mon Mar 07, 2011 3:17 pm

Re: PT 34, S4 (games), Q21 (and other questions like it)

Postby SanDiegoJake » Wed Mar 30, 2011 4:17 pm

Here's a systematic way to attack max/min questions. Let's use this game as an example.

Question: What's the minimum # of docs at Souderton?
Answer choices: 0,1,2,3,4

Step 1: Start with the minimum. Could it be zero?
Answer: no. Why not? What's the first clue you see that tells you it cannot be zero (all docs at Ransb)? Clue 1 tells me nothing about what happens if all docs are at Ransb. Clue 2 gives it up: If J is at Randsb, then O is at Souder. Eliminate zero and Congratulations. You've found your starting point. (any clue that gives you info that it cannot be zero will work as a starting point.)

Step 2: Here's the systematic part! Now that you've identified a reason why it cannot be the minimum, draw out your 3 possible scenarios for this clue. Scenario 1: J at Ransb, O at Souder; Scenario 2: O at Ransb, J at Souder; Scenario 3: Both O and J at Souder. Key moment of insight: Because these are all the possible scenarios with this clue, ONE OF THEM must lead me to the minimum!!!

Step 3: Flesh out each scenario. Lowest # of docs at Souder wins.
Scenario 1: O at Souder, J at Ransb. O brings N to Souder by clue 4. No other automatics. So could 2 be the minimum? Let's see what happens if everyone else goes to Ransb. It won't work by Clue 5. If P is at Ransb, K must be at Souder. So this scenario shows us a min. of 3. We could have O,N,K as only docs at Souder. 3 is the score to beat.

Scenario 2: J at Souder, O at Ransb. Automatics: Clue 5 tells us that if O is at Ransb, P is at Souder. No other automatics. So could it be 2? Let's see what happens if everyone else is at Ransb. No issues there. J,P could be only docs at Souder. 2 is the new score to beat.

Scenario 3: Already starting with 2 in Souder., so this scenario has no chance of winning. Winner: 2 is the minimum.

This approach works for all max/min questions. I'm open to any and all challenges if someone thinks otherwise. Best of luck!

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mac35352
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Re: PT 34, S4 (games), Q21 (and other questions like it)

Postby mac35352 » Thu Mar 31, 2011 11:42 pm

I just finished this game and it took me over 10 mins to finish it. Question 19 took the longest to solve. Can anyone here point me to more in/out games? (in which prep test will I find them)
Thanks!

privatemf
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Joined: Sun Feb 13, 2011 1:15 am

Re: PT 34, S4 (games), Q21 (and other questions like it)

Postby privatemf » Fri Apr 01, 2011 12:42 pm

The Lsat Blog is great and gives you some tips along with were to kind the question types you are looking for. This is what he had on his blog:
Grouping: Selection / In-Out Selection Logic Games, in this order:

PrepTest 33, Game 2 - p. 177 (LSAT Logic Game Explanation: Birds in the Forest | Selection)
PrepTest 36, Game 1 - p. 278
PrepTest 31, Game 2 - p. 85 (very difficult)
PrepTest 30, Game 1 - p. 50
PrepTest 35, Game 1 - p. 236

Then complete the following two games, both of which have numerical distribution elements:

PrepTest 33, Game 3 - p. 178
PrepTest 32, Game 2 - p. 135

http://lsatblog.blogspot.com/2009/12/lo ... agram.html

I hope this helps.

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mac35352
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Re: PT 34, S4 (games), Q21 (and other questions like it)

Postby mac35352 » Fri Apr 01, 2011 1:23 pm

privatemf wrote:The Lsat Blog is great and gives you some tips along with were to kind the question types you are looking for. This is what he had on his blog:
Grouping: Selection / In-Out Selection Logic Games, in this order:

PrepTest 33, Game 2 - p. 177 (LSAT Logic Game Explanation: Birds in the Forest | Selection)
PrepTest 36, Game 1 - p. 278
PrepTest 31, Game 2 - p. 85 (very difficult)
PrepTest 30, Game 1 - p. 50
PrepTest 35, Game 1 - p. 236

Then complete the following two games, both of which have numerical distribution elements:

PrepTest 33, Game 3 - p. 178
PrepTest 32, Game 2 - p. 135

http://lsatblog.blogspot.com/2009/12/lo ... agram.html

I hope this helps.

Thank you for the info.

secretad
Posts: 209
Joined: Tue Jan 04, 2011 11:26 pm

Re: PT 34, S4 (games), Q21 (and other questions like it)

Postby secretad » Fri Apr 01, 2011 2:24 pm

EarlCat wrote:
sea change wrote:I wonder if someone could suggest or point me to some source that suggests a specific process for dealing with with this type of question, i.e. in/out games where you're asked for the minimum or maximum number of elements that could conceivably go in this or that group.

I inevitably end up winging it on these things, which in general does not work out all that well. I'll start with, okay, what if they're all in group X? Most times it's obvious this can't be the case. After that I'm not sure how to proceed and just end up sort of randomly placing variables here and there in a totally nonsystematic fashion and seeing what happens. Time passes; perhaps I've somehow managed to eliminate an answer or two, but I'm still just aimlessly futzing around with various scenarios. I freak out and guess. The end.

Thanks.


Whenever I have a group game with only two places to put my elements, I work it as an in/out game. In this game we are grouping doctors into clinics S and R. I picked S to be "in" and R to be "out." (It doesn't really matter which is which as long as you're consistent.) An "in" element will be designated in my conditionals by its name alone, e.g. "J," and an "out" element will be negated, e.g. ~J.

The rules then form conditionals. For instance, the first rule looks like this:
~K --> J
~J --> K



Is this not backwards? The first rule should be diagrammed the other way.

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EarlCat
Posts: 610
Joined: Mon Mar 12, 2007 4:04 pm

Re: PT 34, S4 (games), Q21 (and other questions like it)

Postby EarlCat » Fri Apr 01, 2011 4:38 pm

secretad wrote:Is this not backwards? The first rule should be diagrammed the other way.

You're right, I wrote it backwards. It's J --> ~K. (fixed)




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