PT78.S2.Q05 (G1) - seven workers

inactive

Hey guys, had a 7Sager message me with a question and I thought you could help out! Here it is:

Hi I had a question regarding the 5th question on Section 2 of preptest 78 (June 2016). you came to the conclusion that B is correct. but cant we also say that A (i.e. QS) is also true? I mean QS were also out so how do we differentiate in the end?
https://7sage.com/lsat_explanations/lsat-78-section-2-game-1/

akistotle

Hi! (A) is wrong because it does not determine the selection.

(A): The fact that Q and S are out does not trigger anything. Q is out, so the first rule goes away. S is out, so the second rule goes away.

But with (B), the selection is completely determined. Q and T are out. T being out kicks S out (/T → /S). Because of W → /R and /V rule, W cannot be in, so W has to be out.

BinghamtonDave

I would like to add a bit to the above explanation. With this question, we are asked to choose the answer choice that if we were to follow what it has asked of us, it will lead to a position where is there is only 1 possible valid world we can construct. Taking a detour here, what does this mean? What does this question mean in theory?

It means that when we select the credited response, the remaining pieces that we can construct a possible world from will interact with our rules in such a way that there will be only 1 possible world. If somehow we can construct more than 1 possible world, after doing what the answer choice has asked us to do, that answer choice has not restricted things enough to fulfill what the question has asked us.

I'm going to go through the answer choices to indicate how when we do what the answer choice has asked us to do, we are left with a group of pieces that do not rise to the standard of the question, i.e. they do not force our remaining pieces into a position where there can be just 1 valid construction (world).

Here are our game pieces:
Q R S T V W X
We are building toward a total of 3/7

(A): We are asked if the removal of Q and S leads to a position where we can choose only 1 valid construction.
Q R S T V W X
With the remaining pieces we can construct the following valid worlds:
RTV
RTX
TVX
This answer choice is not restrictive enough

(C): We are asked if the removal of Q and X leads to a position where we can choose only 1 valid construction.
Q R S T V W X
From the remaining pieces we can select the valid worlds of:
RST
STV
This answer choice is not restrictive enough

(D): We are asked if the removal of R and W leads to a position where we can choose only 1 valid construction.
Q R S T V W X
From the remaining pieces we can select the valid worlds of:
STV
QST
STX
This answer choice is not restrictive enough

(E): We are asked if the removal of R and V leads to a position where we can choose only 1 valid construction.
Q R S T V W X
From the remaining pieces we can select the valid worlds of:
QST
STX
STW

Now take a look at answer choice (B):We are asked if the removal of Q and T leads to a position where we can choose only 1 valid construction.
Q R S T V W X
Wait a second here: we failed the necessary condition of one of our rules: S---->T, therefore we have to also take S out of the mix:
Q R S T V W X

Due to our rules, We cannot select W because from the remaining pieces, the selection of W will not allow us to build towards our required 3 of 7 pieces to construct a valid world.
Q R S T V W X
This leaves us in a position where only RVX can be chosen. This answer choice fulfills the question asked of us.

I hope this helps
David

BinghamtonDave

There is a bit more juice we can get out of this question. This note is a reminder to write a follow up post.