Q26 - All known deposits of the mineral

[ocho34]

I understand why (D) is correct, but could someone explain why choice (E) is wrong? Is it because the answer choice says ANYTHING instead of ANIMAL in the third sentence? (Is the term ANYTHING too general in this case?)

Also, how would I interpret the second sentence in choice (E) and is this sentence one of the reasons why (E) is wrong? Can this be rephrased as saying that the diets of owls consist only frogs?

I am just a bit confused about the wording in answer choice (E). Any help would be appreciated.

[ManhattanPrepLSAT1]

The wording in this question is tough, but there are two problems associated with answer choice (E).

First, in the stimulus it says "All known deposits..." implying that there could be other deposits that we are not aware of. In answer choice (D) it says "The only frogs yet discovered..." which also implies that there may be some frogs that we are not aware of. In answer choice (E) it says in no uncertain terms "Each frog on Scrag Island...".

Second, and this plays off the first, in the conclusion of the stimulus it says that "she is unlikely...". Answer choice (D) says "probably never" and answer choice (E) says that "No owl on Scrag Island will eat anything that lives outside the lagoon." There's just no flexibility in answer choice (E), whereas there is flexibility in the stimulus and answer choice (D).

Your interpretation of the second sentence from answer choice (E) is correct, it's just not the reason why (E) is wrong.

This is a tough question!

[romanmuffin]

I can definitely see why D is the answer, but why can't C be correct?

[ManhattanPrepLSAT1]

Good question. The short answer is that answer choice (C) is a flawed argument, whereas the stimulus is a valid argument.

Answer choice (C) would have been correct if it had limited the frogs to only living in the lagoon. However, instead this argument limits the frogs to being the only animal living in the lagoon. It's possible that the frog's are the only animals living in the lagoon, and yet the frogs also live in other parts of the island. So, the owls may indeed end up eating animals from outside the lagoon.

Make sense?

[mcrittell]

Matt, can you go through every AC for this question please. I think the wording's really tripping me up here.

[OrenBarb]

Matt, can you go through every AC for this question please. I think the wording's really tripping me up here.

I got this right, but worked through it again in conditional terms to see how each answer choice plays out.

First, the stimulus:

All known A (Tanzanite) ----> B (Tanzania). Since C (Ashley’s stone collection) ---> A (Tanzanite), it is unlikely for C (Ashley collecting stones) ---> -B (not from Tanzania).

a) Wrong. A some ---> B. Since C --> A, probably not C --> -B
b) Flawed reasoning. A --> B. Since A ---> C, therefore probably not C ---> _ A.
c) Flawed reasoning. A --> B. Since C --> B. Therefore probably not C and - A.
d) Correct. A (Frogs) --> B (Lagoon). Since C (Diet of all owls) ---> A (frogs), probably not C --> -B
e) A --> B. C ---> A. Therefore, no way to have C --> - B. Close, but this is wrong because of the wording in absolute terms in the conclusion, whereas the stimulus says "unlikely."

[ManhattanPrepLSAT1]

Nice work OrenBarb! I know that there is conditional logic in this one, but it's probably not something I would use to see this argument - which is strange, because I love to use conditional logic!

This is a valid argument since all known deposits of tanzanite originated in Tanzania, and Ashley only collects tanzanite. There is very little chance that she would collect a stone that did not originate in Tanzania.

The argument structure is that of limiting something to one area and then limiting someone to just that something, thereby limiting someone to just that one area.

The correct answer choice (D) limits the frogs to the lagoon. Then limits the owls to eating the frogs, and so can properly conclude that the owls are limited to eating animals from within the lagoon.

(A) does not limit the frogs to just the lagoon, so the argument is flawed in that the owls could be eating the frogs that live outside the lagoon.
(B) fails to say that the owls eat only the frogs. Just because the frogs are eaten only by owls, this still permits the owls to eat something else too.
(C) limits the animals that live in the lagoon to just frogs, but does not limit the frogs to just the lagoon. So the owls could eat the frogs that may live outside of the lagoon.
(E) is the closest of the incorrect answers and while the limitations are appropriate, the strength of those limitations does not match. Notice the strength of the conclusion in the stimulus, which is not a certainty. Answer choice (D) reflects this strength in the conclusion, but answer choice (E) goes a bit too far.

Hope that helps! And again nice work OrenBarb! I just wanted to offer another less formal way of looking at this one.

[timmydoeslsat]

I have a problem labeling this argument as a valid one.

Based on the evidence, how are we to conclude likelihood?

We know that all known deposits of T are in Tanzania. We also know that she collects only T.

However, couldn't it be the case that she is not unlikely to ever collect a stone not originally from Tanzania?

What if it were the case that there is a huge outlay of rocks consisting of the mineral T that is not located in Tanzania? What if this outlay vastly outnumbered the collection of known deposits in Tanzania, say 350 times the number of rocks, which at the current time was unknown to Ashley, but is very close to her next searching grounds.

In this hypothetical, which is consistent with the premises, how could the conclusion still follow of unlikely.

I suppose what irks me is the idea of known rocks and then concluding a probability based on just known. Does not seem to be valid.

[ManhattanPrepLSAT1]

I totally see your point. But what are the chances that such a rock formation exists and that we haven't found it yet? Possible? Yes. Probable? Not Sure. Certain? No.

Since all of the know deposits of tanzanite are located in Tanzania, if someone handed me a piece of tanzanite, I'd be pretty confident that it came from Tanzania. The conclusion is trying to be safe by saying that it's not a guarantee, and because it's acknowledging the possibility that an unknown deposit could all of a sudden be discovered outside of Tanzania - I'd give it to 'em.

[ban2110]

This is more of a general conditional question. How would I go about diagramming a statement like the stimulus' conclusion? Or are such statements generally not diagrammed?

Would it be:
"Z is unlikely ever to collect a Y not originally..." = ~Z-->~Y.

Is this correct?
The double negatives are really confusing me.

[jenniferreisig]

I'm having a really hard time seeing why C in not valid. The language in C is almost verbatim to D and I can't see any difference in meaning. (I just walked myself through it and see the answer now). The last questions in most sections seem to be really tricky.

C. Frogs are the only animals known to live in the lagoon on Scrag Island.
D. The only frogs yet discovered on Scrag Island live in the lagoon.

Is the answer here? I think maybe so. Frogs being the only animals in the lagoon is different than the only frogs discovered live in the lagoon. Oh, so the same frogs that live in the lagoon can live outside the lagoon. They are not restricted to living in the lagoon so therefore the owls can eat an animal living outside the lagoon - what if it sees the same tasty frog living outside the lagoon and its hungry? I see it now.

C. The diet of owls on Scrag Island consists of nothing but frogs from the island.
D. The diet of ALL the owls on Scrag Island consists ENTIRELY of frogs on the island.

Okay, so here D is more explicit in stating ALL and ENTIRELY. Isn't that implied in C? In both the owls eat the frogs on the island. The same frogs that live in the lagoon on the Island.

C. Therefore, the owls are unlikely ever to eat an animal that lives outside the lagoon.
D. So, the owls will probably never eat an animal that lives outside the lagoon.

I see "unlikely ever" and "probably never" to have the same meaning. Not to mention the stimulus states "unlikely ever" in its conclusion so that seems to match nicely. (Now that I see the answer the paired "unlikely ever" in C is a TRICK!).

The minimal differences in C and D are so subtle I am having difficulty seeing why D is a better choice? I'd love some help in my thought process. Thanks!

[maryadkins]

Frogs being the only animals in the lagoon is different than the only frogs discovered live in the lagoon. Oh, so the same frogs that live in the lagoon can live outside the lagoon. They are not restricted to living in the lagoon so therefore the owls can eat an animal living outside the lagoon - what if it sees the same tasty frog living outside the lagoon and its hungry? I see it now.

You got it!

C. The diet of owls on Scrag Island consists of nothing but frogs from the island.
D. The diet of ALL the owls on Scrag Island consists ENTIRELY of frogs on the island.

Okay, so here D is more explicit in stating ALL and ENTIRELY. Isn't that implied in C? In both the owls eat the frogs on the island. The same frogs that live in the lagoon on the Island.

Yeah, they're the same.

I see "unlikely ever" and "probably never" to have the same meaning. Not to mention the stimulus states "unlikely ever" in its conclusion so that seems to match nicely. (Now that I see the answer the paired "unlikely ever" in C is a TRICK!).

Indeed! Well done.