Q12

[Carlystern]

I chose (B) instead of the correct answer (D). I must be totally unclear at what the question stem is asking?

Carly

[ohthatpatrick]

It is quite confusing when you hear "at least one of which must be on the team".

In general, how do you test MUST BE TRUE answer choices?
Do you see if the answer choice is possible or do you see if REFUTING the answer choice is possible?

The latter. Testing to see if an answer choice is possible only tells you that something COULD be true.

In order to know whether it MUST be true, you have to try to 'break' the answer, i.e., come up with a counterexample.

Eliminating answers on Must Be True is kinda like being a snotty, disagreeable teenager.

If an answer choice says that "the earliest F can go is 3"
we think, "Nuh-uh. F can go in 2."

If an answer choice says that "there are at most two people in the Finance group",
we think, "Nuh-uh, it's possible for three people to be in the Finance group".

So when they say "at least one of these two guys must be IN",
we think, "Nuh-uh, it's possible that _______



... it's possible that they're both out.

So we should be analyzing these answer choices by asking ourselves, "Is it possible for BOTH of these guys to be OUT?"

If both people can be OUT together, we'll eliminate the answer.
If both people could NEVER be out together, that will be the correct answer. It must be true that at least one of them is IN.

(A) Can O and S both be OUT? Sure. Neither ~O nor ~S trigger any rules.

(B) Can O and W both be OUT? Sure. Neither ~O nor ~W trigger any rules.

C) Can P and S both be OUT? Sure, in fact we even have a rule that says ~P --> ~S.

(D) Can T and Y both be OUT? No, because of the chain reactions of the rules and the fact that we need 4 people IN.

Rule 3 says that ~Y --> ~W.
Rule 2 says that ~T --> ~S.

Okay, we'll our OUT column has a maximum of four spots. Those spots are now filled.

If Y, W, T, and S are all OUT, then we need to put the other four IN to satisfy the minimum of four IN.

That means that M, P, O, and Z are all IN. But that doesn't work. When M is IN, P and O are OUT.

Since it was impossible for T and Y to both be OUT, (D) is correct to say that at least one of them must be IN.

(E) Can Y and Z both be OUT? Sure. ~Y -> ~W, but Z doesn't trigger any rules. We could have Y, W, Z, and M OUT and have O, P, S, and T IN.

Hope this helps.

[esthertan0310]

If both O and W are out, we can still end up with S P T Z in.

[SamanthaW170]

I was just wondering if there's a quick way to identify which of these answers to test first? I ran through them the same way Patrick did, looking to see if any triggered any rules - but are there things we know about O, S, P, etc. (for example) that might suggest hunting for answer choice D and testing that before the rest?

[ohthatpatrick]

I tend to get suspicious of this line of questioning because it's often easy for us to find a rationale for the correct answer AFTER THE FACT and then blame ourselves (or hold ourselves accountable) for not having been looking for that rationale in the first place.

I certainly don't want to discourage students from "work smarter, not harder" type insights.

I have just found that even at my gray old age of "Sad amounts of LSAT experience", I still find in realtime that I find resorting to plug and chug to be the best way I can guarantee that I'm going to get all the answers right.

So, while reviewing let's look for that cool way of thinking about it, but let's praise ourselves for being able, in realtime, to go quickly
from
"What is the smart thing that they're testing? I can't figure it out"
to
"Screw it ... let me just test these and find out which one breaks"

-----------------

Recent In/Out games have been mainly about placeholders in the OUT column, with a limited amount of OUT column spacing.

In this game, we have at most four things OUT.
And the rules force us to reserve some of those four potential spots with placeholders.

Rule 1 makes us put a M/OP+ in the OUT column. (meaning: every legal OUT column will contain at least M or OP)

Rule 2 and 3 don't give us any placeholders, but they do give us contrapositives that potentially overflow the OUT column.

~P --> ~S
~T --> ~S
~M --> ~W
~Y --> ~W

If I were looking for an answer that was likely to "overflow the OUT column" I would want it to NOT mention my M/OP placeholder (one half of that fraction is already bound to be out --- I want my answer to ADD onto that placeholder minimum in order to get us to more than four out).

So I would prioritize answers that DON'T mention the placeholder people M/OP and look for answers that DO have T, M, or Y, since those all trigger something else being out.

(D) is the only answer with two from that list.

Both T and Y give you someone ELSE that has to be out when they're out, so that's automatically four.

Add in a minimum of one more letter from the M/OP placeholder and you're already over four.

Hope this helps.