Q22

[ManhattanPrepLSAT1]

[andrewgong01]

How do we solve the problem if we do not use previous work? Even after seeing the answer key I am not understanding why the answer would lead us to conclude is L or T that must be in since this game has no rules where something in the "OUT" column forces something else into the "IN" column

[ohthatpatrick]

If you haven't already read my response to your question on Q20 start there, since I'll be assuming you know what I said about the OUT column placeholders in this game.

In order to prove that
"at least one of these two things must be IN",
we have to know "you CAN'T put BOTH things OUT".

What would prevent us from putting any two things OUT? As you said, there are no rules that say "someone OUT forces someone else IN".

It will ultimately hinge on our scarce quantity of OUT spots. We only can have a maximum of four things OUT, because we have a minimum of three IN.

And we already have a minimum of three things OUT, because of our placeholder requirements.
H/SM
M/PT
W/PS

(A) H and S are doable because we could have H, S, M, W and satisfy all three requirements

(B) L and T is not doable because we would be forced to go over four OUT things in order to satisfy our three requirements. Neither L nor T absolved us of any of the requirements. We still would have to satisfy
H/SM
M/P
W/PS
and we only have two more OUT spots available. There's no 2-letter combination that can satisfy those three requirements.

(C) L and W is doable, because L, W, H, M would satisfy all three.

(D) M and P is fine, because M, P, H, W would satisfy all three.

(E) T and W is fine, because T, W, M, H would satisfy all three

What all the doable answers have in common is that one of their members is H, W, or M.

These three letters are the only ones with the power to satisfy one of the OUT requirements using only one letter.

(B) "overflows" the OUT column by not satisfying any of the three placeholders, and therefore adding two MORE out spots onto the minimum of three we already know of.

[hnadgauda]

I don't understand your placeholder explanation and I also don't understand how to choose between answer choices B, C, and E. I understand why A and D are wrong.

After diagramming, I made a t-chart with the following in the out column:
H/M
H/S
M/P
M/T
W/P
W/S

B: L and T are in, then H/S, M, W/P, and W/S have to be out. (Since T is in, M has to be out.)

C: L and W are in, then H/M, M/T, P, and S have to be out. (Since W is in, P and S have to be out.)

E: T and W are in, then M, P, and S have to be out. (Since W and T are in, M and P and S have to be out.)

It seems like all three scenarios are possible. What am I not understanding? Can you please clarify?

[andrewgong01]

I don't understand your placeholder explanation and I also don't understand how to choose between answer choices B, C, and E. I understand why A and D are wrong.

After diagramming, I made a t-chart with the following in the out column:
H/M
H/S
M/P
M/T
W/P
W/S

B: L and T are in, then H/S, M, W/P, and W/S have to be out. (Since T is in, M has to be out.)

C: L and W are in, then H/M, M/T, P, and S have to be out. (Since W is in, P and S have to be out.)

E: T and W are in, then M, P, and S have to be out. (Since W and T are in, M and P and S have to be out.)

It seems like all three scenarios are possible. What am I not understanding? Can you please clarify?

The place holders are
H/SM
M/PT
W/PS

The question is a MBT so to test it I would put the answer choices into the Out Column and see if they still hold. "C" and "E" both work too when you put them both into the out spot.

"L" and "T" does not. Why?
We can Max 4 out. If you put L and "T" this is what we have solved in the Out Column:

H/SM
M/PT
W/PS
T

As we can see no matter how we choose the variables we must exceed 4 outs in this case. For example, You can choose H,M,W to be the remaining outs but that leads you to have more than 4 outs and choosing H, M, W entails the least amount of outs.

I think the key is that (similar to Prep Test 70 Game 2 that had a question just like this) is that certain out placeholder variables are better than others in that some are more "parsimonious" where only having 1 instead of 2 is enough to satisfy that single placeholder. When L and T is chosen, you don't trigger any of the "parsimonious" placeholder variables (namely H,M, and W) and hence by putting in L and T you are essentially wasting 2 spots and you still need to satisfy the 3 remaining placeholders; i.e. of the 3 placeholders there are you did not satisfy any by putting in L and T.

As a counter example, Choice E is "T" and "W". "W" is one of those powerful (parsimonious placeholder) placeholder where in itself it already satisfies one of the placeholders and hence you do not need to have both P and S into the "Out" either. In summary you have a max of 4 "Outs" and hence you can really only afford to waste one of the Out members and Choice B wastes two of the spots because none of them are the parsimonious/powerful placeholder. The key is then to solve the question for what MUST be in revolves around the scarcity of the out column since this game already gives us 3 placeholders and we can only have a max of 4 out; so we can't afford to waste two of the out members that don't satisfy any one of the 3 placeholders

[ohthatpatrick]

Awesome explanation, and I'm totally stealing "parsimonious" placeholder, even though no one but I will enjoy/get it.

Since that poster did NOT seem to like or follow the placeholder logic (hopefully, you went back to the Q20 question referenced in this thread, as the explanation of placeholders was more thoroughly laid out there), here's a quick explanation that doesn't need placeholders.

Since we're doing a "MUST BE TRUE" question, you can invalidate the four wrong answers by counterexamples.

(A) is wrong. I don't HAVE to have one or more of S, H in. It's possible that they're both out.
M W L | S P T H

(C) is wrong. I don't HAVE to have one or more of L, W in. It's possible that they're both out.
S P T | L W M H

(D) is wrong. I don't HAVE to have one or more of M, P in. It's possible that they're both out.
S L T | M P W H

(E) is wrong. I don't HAVE to have one or more of T, W in. It's possible that they're both out.
S L P | T W H M

Hope this helps.