#24 - Local, Must Be True

[Dave Killoran]

Complete Question Explanation
(The complete setup for this game can be found here: lsat/viewtopic.php?t=6157)

The correct answer choice is (A).

The condition in this question stem immediately affects J. From the fifth and seventh rules, J must connect to O and exactly one other island, namely L or M. If any island connected to M cannot also connect to O, and J is already connected to O, then J cannot connect to M and consequently J must connect to L. Accordingly, answer choice (A) is correct.

[Sourpatch]

I’m not sure how to get the right answer for this. Please help.

[Jeremy Press]

Hi Sourpatch,

The best way to approach this question is to think about which island is most strongly affected by the local condition. That's island J.

We know that island J must be connected to O. So the local condition of the question ("no island that is directly connected by bridge with M is also directly connected by bridge with O") tells us right away that J cannot be connected with M. J also can never be connected with K, because K is only connected to one other island and that island must be M or O.

So now we know that J is connected to O, and is definitely NOT connected to M or K. But, from the initial rules, J must be connected to two islands. And the only extra island left as the second one J can be connected to is L. That gets us to answer choice A!

I hope this helps!

Jeremy

[Bmas123]

Hi! Why could this not have been C? If K was connected to O, it would not have to be connected to M. We could stil have J connected to O and J could have connected to either J or L to complete the 2nd line J needed. L could connect to M to satisfy that condition. What am I missing as to why this is incorrect? I think the wording of the question itself is what is really confusing me, if someone could explain that, it would be very helpful. Thank you!

[Luke Haqq]

Hi Bmas123!

We know from the original rules that J is connected with exactly two islands. And we know from the last of the rules that O is one of these islands. That leaves us with one of K, L, or M as the second island to which J is connected. We can eliminate M given the local conditions of this question, leaving us with K or L.

We can eliminate K because of the fourth rule, "J, K, and L are each directly connected by bridge with one or both of M and O," and the sixth rule, "K is directly connected by bridge with exactly one island." K can't connect with J because K is only connected with one other island, and that other island is either O or M.

This leaves us with L as the only other island besides O that J can be connected to under the conditions in this question.