Tricky one, but I would pick A.

Lets just compare A and D.

First D. it compares the total amount of Uranium in seawater and Land. lets just say amount of U in seawater is 1000 and on land its 100. But it doesnt talk about the usage. May its possible that whatever amount is available on land, it'll last forever and we may never need to take it out from seawater

Lets see A. As the U deposit on land is depleting fast, we may landup in a situation where we have to extract U from seawater, even if it costs more than mining on land.

Clearly A wins

Guys, I havent really started studying CR and this is the first time I've come across a question stem like the one mentioned here.

Which of the following would it be most useful to determine in evaluating the argument? -- Does this mean weaken/undermine the argument in this question??

definitely A. It would be economical to use seawater uranium extraction if either cost is reduced or price goes up. The argument states that the cost has to be reduced which is true only is price doesn't go up. Depletion of supply will definitely cause price to go up.

Seems to be A for the reasons mentioned above.

rapid depletion on land will make the extraction from seawater a necessity and hence commercially viable.

My answer is also A.

If I were a VC and need to start doing the business of extracting uranium from sea water, I will go with A because that is the shortest way to determine the success of my venture. Sure, C also helps, but it takes time. And the question is about 'most useful', hence A wins over C.

i"ll go with A...
This Q is about evaluating the argument, If uranium in deposits on land is not rapidly being depleted, then y we should be bothered about technology advances and extracting uranium from seawater

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i can't understand why A is the answer.. i would choose this option only in a "weaken question", but this is an "evaluation question"; my kaplan book says: "The correct answer won't strengthen or weaken the author's reasoning or supply a missing assumption. Instead, the right answer will specify the kind of evidence that you would help you to judge the validity of the author's argument"
this is the reason why i'd chose C
can someone helps me?

We want to evaluate this:

Therefore, until the cost of extracting uranium from seawater can somehow be reduced, this method of obtaining uranium is unlikely to be commercially viable.

Which of the following would it be most useful to determine in evaluating the argument?

a. Whether the uranium in deposits on land is rapidly being depleted
This is the correct answer. If the deposits on land are rapidly being depleted, the uranium's price is going to be higher so despite the high costs, the method of obtaining uranium will be commercially viable.

c. Whether there are any technological advances that show promise of reducing the costs of extracting uranium from seawater
I) show promise of reduce != will reduce
II) determining the possible existence of such technologies does not help us in evaluating the argument
(...) until the cost of extracting uranium from seawater can somehow be reduced (...) <== it has no effect on this

Well this is a toughie.Two options are too close.
Fact 1: Most of the world's supply of uranium currently comes from mines
Fact 2: It is possible to extract uranium from seawater, but the cost of doing so is greater than the price that uranium fetches on the world market.
Conclusion: until the cost of extracting uranium from seawater can somehow be reduced, this method of obtaining uranium is unlikely to be commercially viable

A. Whether the uranium in deposits on land is rapidly being depleted
CORRECT.If the uranium in deposits on land is rapidly being depleted then we have no other choice to shift to some other source .Doesn't matter what the cost of extraction is !
B. Whether most uranium is used near where it is mined
Out of scope. We are concerned about price of extraction not transportation cost or any other thing that this argument is hinting.
C. Whether there are any technological advances that show promise of reducing the cost of extracting uranium from seawater
Incorrect.This is tempting.But i believe the argument is made now so we have to check the validity NOW.The future techs are out of scope.
D. Whether the total amount of uranium in seawater is significantly greater than the total amount of uranium on land
Irrelevant. It doesn't matter how large quantity is available in seawater.If the cost of extraction is high,we will not fetch it.
E. Whether uranium can be extracted from freshwater at a cost similar to the cost of extracting it from seawater
Out of SCOPE.This introduces a new source.We need to evaluate seawater only.

Prem:
Most of the world's supply of uranium currently comes from mines.
It is possible to extract uranium from seawater, but the cost of doing so is greater than the price that uranium fetches on the world market.
Conclusion:
Therefore, until the cost of extracting uranium from seawater can somehow be reduced, this method of obtaining uranium is unlikely to be commercially viable.

Which of the following would it be most useful to determine in evaluating the argument?

A. Whether the uranium in deposits on land is rapidly being depleted
>>
Yes: Price in market would rise and hence current price difference would go down.
No:Strengthens/agrees with conc.

B. Whether most uranium is used near where it is mined
>>Arg is abt extracting uranum from sw.
C. Whether there are any technological advances that show promise of reducing the cost of extracting uranium from seawater
>>Yeah, this was a trap for me.But i rejected it, using the variance analysis.
D. Whether the total amount of uranium in seawater is significantly greater than the total amount of uranium on land
>>Not relevant.
E. Whether uranium can be extracted from freshwater at a cost similar to the cost of extracting it from seawater
>>Same as D.

Found a very nice explanation on manhattangmat.
here is the link for that http://www.manhattangmat.com/forums/mos ... t3508.html

whoa, no, guys. that's not the issue here.

the problem is this:

the argument says
until the cost of extracting uranium from seawater can somehow be reduced, this method of obtaining uranium is unlikely to be commercially viable.

in other words, the argument is saying that the ONLY WAY that seawater extraction will be commercially viable is if the cost of that extraction comes down.

to weaken the argument, then, you need to find ANOTHER way in which seawater extraction will be commercially viable, WITHOUT a cost reduction.
this is what choice (a) does. if the uranium on land is being depleted, then extracting uranium from seawater will become "commercially viable", out of pure necessity. the cost will go up, but that's the breaks.

choice (c) doesn't actually affect the argument at all, because the argument already acknowledges that uranium will become commercially viable IF the price comes down.

--

analogy:
if i tell you this:
unless you eat my fish 'n' chips, you'll never know the true meaning of gastronomic ecstasy

then:
* if you say "eating your fish 'n' chips will give me gastronomic ecstasy", then that doesn't affect my statement at all, because you're just echoing what i've already told you.

however:
* if you say "au contraire, i can also get gastronomic ecstasy from a nice fat slice of meat lover's pizza", then that weakens my argument, because i'm telling you there's only one source of gastronomic ecstasy but you're countering with another.

substitute
fish 'n' chips --> cost increase
pizza --> depletion of land resources
gastonomic ecstasy --> commercially viable
...and there you have it.

Before everything, let's break down the prompt into pieces
• Uranium mostly come from mines. An alternative source would be from seawater, but it is too costly.
• Argument: Cost of extracting uranium from seawater should decrease to consider this option.

(A) Whether the uranium in deposits on land is rapidly being depleted
- Correct answer. It is important to know whether mining uranium will still be a viable option or not. If it is rapidly depleting, obtaining uranium from seawater will be the ONLY viable option. If it is not rapidly depleting, then it is not a viable option.
(B) Whether most uranium is used near where it is mined
- This is irrelevant to the argument, as this does not address whether extracting uranium in seawater could be an option
(C) Whether there are any technological advances that show promise of reducing the costs of extracting uranium from seawater
- This is future-driven. If there are technological advances that show promise of reducing the cost, it still does not make uranium extraction from seawater a viable option for now.
(D) Whether the total amount of Uranium in seawater is significantly greater than the total amount of uranium on land
- Irrelevant. What is important is the costly process of extraction, and not necessarily the total amount of uranium that can be extracted
(E) Whether uranium can be extracted from freshwater at a cost similar to the cost of extracting it from seawater.
- The question is whether it will be better to extract uranium in the mines or from seawater. And if it is too costly to extract from seawater, it would be efficient to extract from mines. This does not make extracting from seawater a viable option for now.

This is a great question and I just want to add my two cents to clarify the difference between A & C. I picked A first and then started thinking about C which also makes a lot of sense. But here's my reasoning for why C is definitely wrong.

A) Correct answer because, if land deposits are running out in 10 years then extracting from seawater becomes a necessity. At that point think about supply and demand, when the supply decreases, demand increases and the price goes up. Therefore at some point it becomes commercially viable. Now think about OIL, when the price of oil is $40 a barrel, it becomes commercially unprofitable to dig oil out of Alberta's tar sands, so companies stop extracting it. But when the price goes up, they start extracting because it becomes commercials viable. Demand has a huge impact on the price. Now imagine if all the Oil in the world ran out and we found oil on the Moon, would it become commercially viable to go to the moon? Yes, people would start going to the Moon to get oil. So think about that.

For C) many people are stuck with this option, I also thought this might be correct BUT, think about the supply. IF the supply of land uranium is unlimited, it will never run out, so even if there's new technology then that technology might make it cheaper to extract from land. (There is a lot of uncertainty). So think in terms of extremes, unlimited resources on land, therefore we may never have to extract from water, even if it becomes cheaper than it was before. Say Extracting from land = $1, and extracting from water = $10, even if the cost of extracting from water comes down to $5 with new technology, its still cheaper to get it from Land. So without knowing the cost of each method and supply, we can't answer with C.

So the answer is A. Hope this helps!
_________________

Most of the world's supply of uranium currently comes from the mines. It is possible to extract uranium from seawater, but the cost of doing so is greater than the price that Uranium fetches on the world market. Therefore, until the cost of extracting uranium from seawater can somehow be reduced, this method of obtaining uranium is unlikely to be commercially viable.

Which of the following would it be most useful to determine in evaluating the argument?

a. Whether the uranium in deposits on land is rapidly being depleted
b. Whether most uranium is used near where it is mined
c. Whether there are any technological advances that show promise of reducing the costs of extracting uranium from seawater
d. Whether the total amount of Uranium in seawater is significantly greater than the total amount of uranium on land
e. Whether uranium can be extracted from freshwater at a cost similar to the cost of extracting it from seawater.

My 2 cents.

Premise 1 : Most uranium comes from mines
Premise 2 : cost of extraction from sea > world market price
Conclusion : Unless cost goes down, extraction from sea is not viable --> which means, stick with mining from land.

I was between A and C and eliminated C because although it is tempting, technology is not mentioned in the stem.
A is correct because, if uranium from land is no longer possible due to depletion, then people will be forced to extract from sea, pushing the price up.

why not (b)? since most of the uranium is used where it is mined then there can be reason to extract uranium at those places where there are no mines to meet the local demand making it commercially viable.

The conclusion is that "until the cost of extracting uranium from seawater can somehow be reduced, this method of obtaining uranium is unlikely to be commercially viable." According to the author, the only way that extracting uranium from seawater will likely become commercially viable is if the COST of that method is decreased. But what if the PRICE that Uranium fetches on the world market increases? In that case, the seawater method could become commercially viable even if the cost does not decrease.

In order to evaluate the author's argument, we would want to know whether the price of Uranium is likely to increase, so (A) is the best choice.

As for choice (B), if the cost is greater than the price, then the method is not economically viable. We are told that the cost of the seawater method is currently greater than the price, REGARDLESS of where the Uranium is used.

Imagine a city with a high demand for Uranium, so you open a seawater extraction plant nearby. In order to be commercially viable, you'd still have to sell your Uranium at a price that exceeds the cost. But if that price exceeds the world market price, the city will buy it's Uranium from elsewhere, even though your plant is closer.

Sure, we could come up with hypothetical situations in which choice (B) might be relevant (i.e. something about transportation costs?), but in order to evaluate the specific argument in this passage, choice (A) is the most relevant and useful.
_________________

You mentioned that we need to evaluate along the COST, PRICE line. In that case why is C wrong which says the the cost will decrease based on technological advancements