#20 - Local, Must Be True

[Dave Killoran]

Complete Question Explanation
(The complete setup for this game can be found here: lsat/viewtopic.php?t=2416)

The correct answer choice is (B)

The question stem sets up the following situation:

D91_Game_#4_#20_diagram 1.png

Since Dave must fly with Bob or Cindy, if Cindy flies on plane 3, then Bob must fly with Dave in plane 2. It follows that answer choice (B) is correct.

Answer choice (E) is incorrect since once it is established that Cindy flies with Dave on plane 2, Bob would then be free to fly on any plane.

[gibb3710]

Hi,

I am not totally understanding why (E) is wrong . Is it not saying the exact same thing as (B)? If Cindy flies with Dave on plane 3 why does Bob need to fly plane 2? My understanding is that Dave flies in plane 2 he needs either Bob or Cindy. So essentially it looks to me like (B) and (E) are saying the same thing. I answered all the other questions quickly with no problems but this one is not making sense hahah.

Thanks.

[Dave Killoran]

Hi,

I am not totally understanding why (E) is wrong . Is it not saying the exact same thing as (B)? If Cindy flies with Dave on plane 3 why does Bob need to fly plane 2? My understanding is that Dave flies in plane 2 he needs either Bob or Cindy. So essentially it looks to me like (B) and (E) are saying the same thing. I answered all the other questions quickly with no problems but this one is not making sense hahah.

Thanks.

Hi Gibb,

Thanks for the question! Answer choices (B) and (E) are not identical, and the difference between them is one worth studying

The key to the problem is knowing that Dave must fly with Bob or Cindy. This condition has to be met, and so it controls what occurs. But, in this particular problem, we also know from the question stem that Dave flies in plane 2. Now, compare that to (B) and (E), where I've added italics for emphasis:

• (B) If Cindy flies in plane 3, Bob flies in plane 2.
  (E) If Cindy is in plane 2, Bob flies in plane 3.

So, in answer choice (B), when Cindy flies in plane 3, who is left to fly with Dave in plane 2? Only Bob remains available because Cindy is in 3 and Anna is in 4. Thus, the second half of (B) must occur: "Bob flies in plane 2." Answer choice (B) must be the case then.

Now look at answer choice (E). Once Cindy is in plane 2, then Dave is covered since he has a pilot. What does that do to Bob? Nothing at all, and he's now free to go wherever he wants. He definitely doesn't have to fly in plane 2 because Dave is already covered by Cindy being in plane 2.

Knowing Dave is in 2 and needs Bob or Cindy is the key, and then look at how each answer starts—where Cindy goes (or doesn't go) makes all the difference!

Please let me know if this helps, thanks!

[amoomey]

The question is for the online homework - December 1991 Digital LG 20.

This is the game about pilots and copilots. I approached the entire game wrong because I recognized that there are only 3 qualified pilots and assumed then that the qualified pilots could be used more than once to fill the 4 available planes. (this is consistent with the fact that the premise/rules do not say that a qualified pilot can only be used once and the fact that it does not state that the planes are all flying at the same time in the airshow)

However, the game also does not state that all 4 planes must be used. So, my question is, how am I supposed to know to guide myself to the use of only 3 planes and know that each pilot can only be used once? When thinking about it, I can't find anything that would prevent this confusion and might even go as far to say that this question arguable.

[Stephanie Oswalt]

The question is for the online homework - December 1991 Digital LG 20.

This is the game about pilots and copilots. I approached the entire game wrong because I recognized that there are only 3 qualified pilots and assumed then that the qualified pilots could be used more than once to fill the 4 available planes. (this is consistent with the fact that the premise/rules do not say that a qualified pilot can only be used once and the fact that it does not state that the planes are all flying at the same time in the airshow)

However, the game also does not state that all 4 planes must be used. So, my question is, how am I supposed to know to guide myself to the use of only 3 planes and know that each pilot can only be used once? When thinking about it, I can't find anything that would prevent this confusion and might even go as far to say that this question arguable.

Hi amoomey!

Thanks for the post! I have moved your post to the thread discussing #20. There is also a link to the full setup above as well. Please review the above discussion, as well as the setup discussion, and let us know if that helps, or if you have any further questions.

Thanks!

[amoomey]

The question is for the online homework - December 1991 Digital LG 20.

This is the game about pilots and copilots. I approached the entire game wrong because I recognized that there are only 3 qualified pilots and assumed then that the qualified pilots could be used more than once to fill the 4 available planes. (this is consistent with the fact that the premise/rules do not say that a qualified pilot can only be used once and the fact that it does not state that the planes are all flying at the same time in the airshow)

However, the game also does not state that all 4 planes must be used. So, my question is, how am I supposed to know to guide myself to the use of only 3 planes and know that each pilot can only be used once? When thinking about it, I can't find anything that would prevent this confusion and might even go as far to say that this question arguable.

Hi amoomey!

Thanks for the post! I have moved your post to the thread discussing #20. There is also a link to the full setup above as well. Please review the above discussion, as well as the setup discussion, and let us know if that helps, or if you have any further questions.

Thanks!

Hello, I don't feel my question has been answered after reviewing the thread. I had already seen the explanation of setup and of each question, but my outstanding question applies to the fundamental understanding of game. My error led me down a destructive path when it came to answering questions.

[Rachael Wilkenfeld]

The question is for the online homework - December 1991 Digital LG 20.

This is the game about pilots and copilots. I approached the entire game wrong because I recognized that there are only 3 qualified pilots and assumed then that the qualified pilots could be used more than once to fill the 4 available planes. (this is consistent with the fact that the premise/rules do not say that a qualified pilot can only be used once and the fact that it does not state that the planes are all flying at the same time in the airshow)

However, the game also does not state that all 4 planes must be used. So, my question is, how am I supposed to know to guide myself to the use of only 3 planes and know that each pilot can only be used once? When thinking about it, I can't find anything that would prevent this confusion and might even go as far to say that this question arguable.

Hi amooney,

This game is often frustrating for exactly that reason. It's an old game (originally given in the 80s I think!), and I believe that modern tests would have language to clarify the issue (ie saying that each plane flies exactly once, or that a person can only fly once, or similar language). With the rules as they are given, we can get that each pilot flies only once because it doesn't tell us that the planes fly at different times. They are numbered, but the numbers are not given in a time-based order. The planes all fly in a show, and they each need a pilot. There's no rule to say that a pilot can occupy multiple planes, so we don't use them multiple times.

There's also a key difference in wording used between the pilots/copilots and the planes. The planes are all "available" while the pilots/copilots are "all aboard planes that fly..." which indicated that the people must all be used, but the planes are only optionally used. Similarly, the language in the rule "no plane flies without a qualified pilot" gives us another clue that planes do not all have to fly.

Hope that helps!