## Getting faster at In/Out grouping

Prepare for the LSAT or discuss it with others in this forum.
Mr.Binks

Posts: 574
Joined: Wed Feb 16, 2011 12:49 pm

### Getting faster at In/Out grouping

Evening mates,

Although I can always get the right answer for In/Out grouping games, it seems to take me a bit longer than I'd like, especially for the global type questions (e.g., Which of the following must be true?).

Does anyone have any recommendations (aside from a lot of drilling) that could help me move a bit faster through these?

lovejopd

Posts: 544
Joined: Tue Dec 01, 2009 1:00 pm

### Re: Getting faster at In/Out grouping

Hey buddy, good to see you again

Do you know/remember which game(s) in a specific prep you have a trouble with?

I think for In/Out game,
1. it is important to have a better conditional logic+inference
2. Use "Place holder" and know how many slots are left
3. Don't spend time for writing every contrapositive of the rule IF you are good at making inferences in your head

Ex) Most common rules in In/Out
1) A and B cannot be selected together = If A is selected, B cannot be included
--> I put "A/B" in the "Out" group(Place Holder) and write "A-/-B" Above "In" group set-up
Only 3 scenarios depending other relevant conditions though-1) A, 2) B, 3) None

2) If A is NOT selected, B must be selected
--> I put "A/B" in the "In" group(Place Holder) and write "A-/-B" Above "Out" group set-up

3) If A is selected, B also must be selected
--> Not a lot of inference, you could write down contrapositive
A--> B (=~B -->~A)

If you could do this stuff without thinking too much, you could save tons of time in In/Out-selection game

HTH <3

chem!

Posts: 9576
Joined: Sat Dec 03, 2011 8:03 pm

### Re: Getting faster at In/Out grouping

I'm a fan of Manhattan's Logic Chain.

Mr.Binks

Posts: 574
Joined: Wed Feb 16, 2011 12:49 pm

### Re: Getting faster at In/Out grouping

Yeah, I think the thing that bogs me down the most is trying to make sense of how all the conditional statements work together.

Oh, another thing:

I use your placeholder method as well, but I get confused when there's a rule such as A --> ~B & ~C. Clearly, there's a placeholder in the "out" section, but which one (of B and C) do you choose to put there?

Chem: it's your birthday. Quit doing LSAT!

lovejopd

Posts: 544
Joined: Tue Dec 01, 2009 1:00 pm

### Re: Getting faster at In/Out grouping

Mr.Binks wrote:Yeah, I think the thing that bogs me down the most is trying to make sense of how all the conditional statements work together.

Oh, another thing:

I use your placeholder method as well, but I get confused when there's a rule such as A --> ~B & ~C. Clearly, there's a placeholder in the "out" section, but which one (of B and C) do you choose to put there?

Chem: it's your birthday. Quit doing LSAT!

For rules that have more than 2 variables, placeholder does not work well(not advantageous). HOWEVER, these rules are often used for a question like a minimum/maximum number for In and Out section. You know what I am talking about. If you want a minimum number for "In" section OR a maximum number for "Out" section, you are more likely to put A in "In" Section" rather than trying B or C in "in" Section.

A -->~B AND ~C
=B OR C --> ~A

As another poster points out, tree system can be helpful for this type of questions.
Ex) another rule says that D --> B (which means A -->~B -->~D, you are better off using A for a minimum "in" section as you can put B, C, and D in "Out" section. HTH
Last edited by lovejopd on Wed May 30, 2012 11:15 am, edited 1 time in total.

Lyov Myshkin

Posts: 218
Joined: Sat Jun 28, 2008 11:28 pm

### Re: Getting faster at In/Out grouping

i studied the crap out of this back in the day, and have always considered it indispensable towards my strategy towards these types of games.

http://www.griffonprep.com/Birdgamesolution.html

LexLeon

Posts: 397
Joined: Fri Oct 07, 2011 11:03 pm

### Re: Getting faster at In/Out grouping

Some things that I've learned:

1. Know conditional logic like the back of your hand. You should be able to translate any rule or hypothetical into letters, arrows, or slashes in the blink of an eye. I imagine that the words "unless", "either...or, but not both", etc. might give a large number of people some trouble. Do not be one of those people.

2. Draw all inferences before you begin. Normally, it's a list of like 8, or something. And when I mean all, I don't mean that you need to write the contrapositive of each; for the contrapositive, as you should at all times reckon, is transparently logically equivalent to its contrapositive.

3. Write transitive statements with only one arrow for maximum clarity. In other words, if given:

"X is in the cave only if Y is;
Z cannot be in the cave unless X is."

Write Z --> X and Z--> Y, not Z--> X--> Y. Though, this may be simply an idiosyncratic matter of preference.

4. On a question that asks for a complete and accurate list, automatically cogitate or transcribe the list of things included (if asked for a complete list of what's not included) or not included (if asked for a complete list of what's included). From there, it's usually only a lightning fast revision of the rules between you and the CR.

The beauty of these (the straightforward in/out selection games, like birds, trees, and fruits) is that the only options for each variable are--you guessed it--in or out; it's not like each could be in one of three groups, or two of four groups, or first, second, third, fourth, fifth, sixth, or seventh in a sequence. However, in hybrid games in which there are the above obfuscatory complexities, the advice I've offered you may well apply there too.

buckilaw

Posts: 839
Joined: Fri May 07, 2010 1:27 am

### Re: Getting faster at In/Out grouping

glucose101

Posts: 409
Joined: Sun Mar 29, 2009 12:23 am

### Re: Getting faster at In/Out grouping

I used to use MLSAT's method, but I found it didn't account for games w placeholders as much as Velocity's method. Velocity FTW!

princeR

Posts: 291
Joined: Mon Dec 05, 2011 4:10 pm

### Re: Getting faster at In/Out grouping

A good tip demonstrated by example, than I'll explain it a little bit:

If not A than B
~A-->B
~B-->A

Notice that the two necessary conditions are the same, as in, they are both positive and not negated. This means that no matter what one of these will have to be IN. So, when I create my diagram, I will write in the IN column, "B/A" reminding myself that I always need at least one of them.

If A than not B
A-->~B
B-->~A

Again, notice how our two necessary conditions are the same, as in, they are both negative and not positive. Thus, we know that we are going to need one of these in our OUT column. So, again, like in the above example, I will write in my OUT column, "~B/~A" reminding myself that one of these needs to be out.

This really helps in remembering what variables you need to be keeping an eye on. Furthermore, for those questions of, "whats the maximum/minimum that could be IN/OUT" you can refer back to these and see that you will need one of these no matter what, and than do a hypothetical with them and get an answer pretty damn fast.

I love IN/OUT games. I find them to be very easy. This is subjective, but I hope we get 2, maybe even 3 in June!

TERS

Posts: 161
Joined: Thu May 24, 2012 11:29 pm

### Re: Getting faster at In/Out grouping

Mr.Binks

Posts: 574
Joined: Wed Feb 16, 2011 12:49 pm

### Re: Getting faster at In/Out grouping

princeR wrote:
I love IN/OUT games. I find them to be very easy. This is subjective, but I hope we get 2, maybe even 3 in June!

I will punch you in the ovaries if we get 2 or 3 in June.

Simple ordering games all the way!

princeR

Posts: 291
Joined: Mon Dec 05, 2011 4:10 pm

### Re: Getting faster at In/Out grouping

TERS

Posts: 161
Joined: Thu May 24, 2012 11:29 pm

princeR wrote: