In the past the country of Malvernia has relied heavily on imported

A "most useful to evaluate" question is typically best approached from a weaken mindset. Look to establish the conclusion and premises, decipher the gap in logic, and then think about how you would attack the gap. The correct answer will be focused on one of the gaps in logic.

Here the argument states that while Malvernia relied heavily on imported oil in the past, the company has implemented a program to convert heating systems from oil to natural gas, and the country is steadily increasing its oil production each year. From these premises the argument concludes that, if these trends continue, Malvernia is likely to experience a reduced dependency on foreign oil in the future. The primary gap in logic here is that this argument is focused on the supply of oil increasing and then one demand of the oil potentially decreasing (heating systems). However, there could be many other oil demands that increase drastically, potentially more than offsetting these factors. Answer D correctly addresses this, because if the amount of oil used for generating electricity and transportation increases greatly, Malvernia may end up depending even more on foreign oil, not less, and thus the conclusion would not hold.

Answer choice A is a pretty irrelevant comparison. Even though Malvernia currently produces more natural gas than it uses, it may just use essentially zero natural gas. Answer choice B is completely out of scope - other countries don't matter. Answer choice C is also out of scope - the argument is not discussing alternative energy sources. And answer choice E is irrelevant. Knowing whether any systems have currently been converted (may 1 has, maybe 1,000,000 have) or not doesn't affect this argument.

I hope this helps!

In the past the country of Malvernia has relied heavily on imported oil. Malvernia recently implemented a program to convert heating systems from oil to natural gas. Malvernia currently produces more natural gas each year than it uses, and oil production in Malvernian oil fields is increasing at a steady pace. If these trends in fuel production and usage continue, therefore, Malvernian reliance on foreign sources for fuel is likely to decline soon.

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

(A) When, if ever, will production of oil in Malvernia outstrip production of natural gas?
(B) Is Malvernia among the countries that rely most on imported oil?
(C) What proportion of Malvernia's total energy needs is met by hydroelectric, solar, and nuclear power?
(D) Is the amount of oil used each year in Malvernia for generating electricity and fuel for transportation increasing?
(E) Have any existing oil-burning heating systems in Malvernia already been converted to natural-gas-burning heating systems?

Malvernia

Step 1: Identify the Question

In the question stem, the words useful to establish in evaluating indicate that this is an Evaluate the Argument question.

Step 2: Deconstruct the Argument

Past: M lots I oil

Recent: heating oil → gas

Now: make > gas than use

oil prod incr steady

If trends cont → M rely less on foreign fuel

The conclusion is in the form of an if-then statement: If these trends continue, then something else will happen. It’s important to note that the author’s argument is predicated on the idea that the trends will continue. Don’t fall into a trap based on the possibility that the trends will not continue; the author hasn’t concluded anything about what might happen if the trends do not continue. The author is only claiming that her conclusion is true if M continues to produce more gas each year than it uses and if oil production keeps increasing at a steady pace.

What does this argument assume? M already has to import oil, but the argument assumes that increasing oil production at a steady pace will allow the country to reduce its oil imports. What if M’s oil consumption is increasing at a much greater pace than its oil production?

Step 3: Pause and State the Goal

On Evaluate questions, the answers will be in the form of a question or a “whether x is true” statement. The correct answer will address an issue on which the argument hinges, depending on whether that statement is true: one way, the argument will be strengthened; the other way, the argument will be weakened.

Step 4: Work from Wrong to Right

(A) The argument does not provide any detail about the relative amounts of oil vs. gas production. Whether M’s oil production outstrips gas production next year or in 20 years, it is still unclear whether the country needs more oil than it produces.

(B) The argument does not compare M to other countries. It is focused solely on whether M will continue to need to import foreign fuel.

(C) If 3% of M’s total needs are currently met by these other energy sources, nothing is changed about the current oil and gas needs as stated in the argument. If 50% of M’s total needs are currently met by these other energy sources, it is still the case that current oil and gas needs are the same as in the argument.

(D) CORRECT. If M needs an increasing amount of oil every year for other uses (electricity and transportation), then it may be the case that M’s oil production is not increasing at a fast enough rate to keep pace with demand. In this case, the argument is weakened. If, on the other hand, M does not need an increasing amount of oil every year for these other needs, then it may be the case that M’s oil production is increasing at a fast enough rate to keep pace with demand, in which case the argument is strengthened.

(E) If none have already been converted, the argument is not impacted because the conclusion is claimed to happen soon; the argument does not say that the conclusion has already occurred. If 1,000 have already been converted, the argument is still not impacted, because the conclusion is still set in the future.

Hi guys,

Looks like there's some confusion on this one, so let's give it a closer look. Thabk's emphasis on the conclusion is important (and correct). When a CR question asks what would be most useful to evaluate "the argument", really it is asking you what would help evaluate the conclusion. The conclusion here is clearly marked by the keyword "therefore": "Malvernian reliance on foreign sources for fuel is likely to decline soon."

And what would help evaluate the conclusion? An answer choice that will (depending on what is established) either strengthen or weaken that conclusion. So really, you can treat this kind of question as either Strengthen or Weaken, but in my experience it's usually easiest to treat these "useful to evaluate" questions as Weaken. Think of it this way: The author's argument is missing some information (what it would be useful to establish), and therefore there is a gap between his evidence and his conclusion. The correct answer would expose that gap, just as it would in a standard Weaken question.

To the stimulus. On first reading, it seems like a pretty reasonable argument. The Malvernians have relied on imported oil in the past, but they may be able to turn that around, for two reasons:

1. They're switching from oil to natural gas, of which they have a plentiful supply.
2. Domestic oil production is increasing.

If domestic oil supply is going up and demand is going down, it seems almost inevitable that their reliance on imported oil will decrease. However, note the limited scope of the first premise: they aren't switching ALL oil usage to natural gas, only the fuel used in their heating systems. We actually don't know anything about the overall demand for oil. That is the gap in the author's reasoning. Choice D exploits this gap: if the amount of oil used for non-heating purposes (generating electricity and transportation) is increasing, then the overall demand for oil might still be increasing too fast for domestic oil production to keep pace (even though production is increasing as well).

E seems to be the most popular wrong answer choice, so let's talk about that one too. It references the heating systems mentioned in the stimulus, so it's tempting. However, remember that we need to evaluate the conclusion. Will the fact that some oil-burning systems have already been converted to natural gas affect whether Malvernian reliance on foreign sources for fuel "is likely to decline soon"? Not really. Whether the conversions have already started or not, they will happen, so in effect this answer neither adds to nor takes anything away from the argument. Now, you could get into all sorts of complicated logic to convince yourself that E is the answer -- Like, maybe because the conversions have started, that means that the all the conversions will happen faster, and maybe if the conversions happen faster it's more likely that reliance on foreign oil will decline soon... Maybe, maybe, maybe. This kind of speculative thinking is never required on the GMAT (and in fact can be disastrous). The correct answer on a Strengthen or Weaken question must DIRECTLY affect the conclusion -- not after multiple steps. Don't overthink CR answer choices!

However, as this question shows, it is extremely important to read the stimulus carefully and note the specific wording involved. Better to spend a little extra time up front to understand the stimulus rather than flounder around with the answer choices, not knowing what you're looking for. Ideally on this question you would be able to predict, in vague from, what the answer will look like before reading the answer choices. However, this isn't always possible. As long as you have a good understanding of the stimulus you should be fine.

Hope that sheds some light on this question.

Happy studying...

Solution
passage analysis          
                                                   
In the past the country of Malvernia has relied heavily on imported oil.

In order to meet the domestic demands, the country of Malvernia used to depend heavily on imported oil.

Malvernia recently implemented a program to convert heating systems from oil to natural gas.

Recently Malvernia put into effect a program that would change the requirements of heating systems in the country. The heating systems that used to run on oil will now run on natural gas.

Malvernia currently produces more natural gas each year than it uses,

At present, the country’s annual production of natural gas exceeds the demand for it.

and oil production in Malvernian oil fields is increasing at a steady pace.

And the Malvernian oil fields are stepping up their oil production at a steady rate.

If these trends in fuel production and usage continue, therefore, Malvernian reliance on foreign sources for fuel is likely to decline soon.

If Malvernia continues to produce more natural gas each year than it can use and if its oil production keeps increasing at a steady pace, then it will not need to import oil.

Conclusion:
If Malvernia continues to produce more natural gas each year than it can use and if its oil production keeps increasing at a steady pace, then it will not need to import oil although it had heavily relied on imported oil in the past.

pre-thinking                                                                 
Falsification question

In what scenario will Malvernia still need to import oil?
Given that →The heating systems that used to run on oil will now run on natural gas.
                  → At present, the country’s annual production of natural gas exceeds the demand for it.
                  →the Malvernian oil fields are steadily stepping up their oil production


Thought Process

The picture that is painted here is that on one side the demand for oil will go down (heating systems will convert from oil to natural gas) and on the other side the domestic production of natural gas and oil will increase. And so, the necessity to bring in oil from outside will reduce. However, what if the demand also goes up with the increase in production of gas and oil to the extent that it outstrips the domestic supply?


Falsification condition

What if the domestic demand for oil and natural gas also keeps increasing at a significantly higher pace than the pace of production of oil and natural gas?

In that case, the demand may soon outrun the supply/production and Malvernia might need to continue to import oil despite its energy fuel production trends.

Assumption 

The domestic demand for oil and natural gas will not increase at a significantly higher rate than the rate of production of oil and natural gas.

Answer Choice Analysis

A
Currently, the heating systems are going to use gas instead of oil. So anyways the requirement for oil is going to go down. And we know that the production of both gas and oil is on the increase. Does the time matter in this scenario? No. Because either way, it does not impact my conclusion.

Hence, it is not the correct choice.

B
Since the passage only talks about the scenario at Malvernia, this is irrelevant.

Hence, incorrect choice.

C
Even if we get to know the proportion of current energy needs met by hydroelectric, solar, and nuclear power, etc., it does not rule out the possibility of declining oil imports because the fact remains that oil production is increasing steadily.

Hence, this is not the correct option.

D
In other words, this question seeks to know whether the requirement/demand for oil is increasing in Malvernia. The answer to this is in line with our pre-thinking assumption.

Let us use the variance test to be doubly sure.

Yes- The amount of oil used each year in Malvernia for generating electricity and fuel for transportation IS increasing
In this case, there might arise a situation where Malvernia might still need to import oil in spite of its increasing oil production in order to keep up with the demand. This weakens our belief in the conclusion.

No- The amount of oil used each year in Malvernia for generating electricity and fuel for transportation IS NOT increasing
On the other hand, this extreme strengthens our belief in the conclusion. If this is true, then Malvernia will have an excess supply of oil over its demand and will not need to import oil.

Hence, this is the correct answer.

E
If the conversion has already been done, then that has already been accounted for by the argument which talks about the near future situation after the implementation of the oil to gas conversion program. This does not impact our conclusion.

Hence, this is not the correct choice.
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In the past the country of Malvernia has relied heavily on imported oil. Malvernia recently implemented a program to convert heating systems from oil to natural gas. Malvernia currently produces more natural gas each year than it uses, and oil production in Malvernian oil fields is increasing at a steady pace. If these trends in fuel production and usage continue, therefore, Malvernian reliance on foreign sources for fuel is likely to decline soon.

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

(A) When, if ever, will production of oil in Malvernia outstrip production of natural gas? - evaluating this is irrelevant. this does not test if the replacing natural gas with oil, and with oil production increasing foreign dependency will stop.

(B) Is Malvernia among the countries that rely most on imported oil? - out of scope

(C) What proportion of Malvernia's total energy needs is met by hydroelectric, solar, and nuclear power? - again, introducing new elements. out of scope

(D) Is the amount of oil used each year in Malvernia for generating electricity and fuel for transportation
increasing? - same as C, introducing new elements. If the question was evaluating the conclusion THEN this would be the best to evaluate "indeed if reliance on foreign countries on oil will decrease"

(E) Have any existing oil-burning heating systems in Malvernia already been converted to natural-gas-burning
heating systems? - this helps to evaluate the argument as per stated in the argument "Malvernia recently implemented a program to convert heating systems from oil to natural gas - and required to evaluate the argument

E it is

I actually understand this reasoning, but I can't drift away from considering (B) a valid option. I mean, if we evaluate this statement: Malvernia is a country that rely on imported oil. I was indecisive between (B) and (D) and eventually went with (B), it kinda makes sense, no? What if it relies heavily on imported oil, say, for any other production.

So we already know that Malvernia relies heavily on foreign oil, that is given. Answer choice B only addresses other countries, and whether they rely more or less on foreign oil. Other countries don't matter at all, and that puts B very much out of scope.

I hope this helps!

Import = Demand – Supply

Import of Natural Gas and Oil = (Demand – Supply)NG + (Demand – Supply)oil

Now, we know that the first parenthesized expression is negative and in the second expression, we are only told about supply of oil, not the demand, so the answer choice must be talking about demand of oil.

We see that option D and option E talk about the demand of oil. So, options A, B and C can be eliminated right away.

While option D directly asks whether oil consumption is increasing or not, option E talks about shifting of consumption from oil to natural gas. Since, we are concerned about import of both oil and natural gas; a shift from oil to natural gas will not impact us. It’ll only change whether we need to import oil or natural gas.

Thus, option D is the correct choice.
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Veritas Prep take on the problem

Let’s break down each answer choice:

(A) The question of when production of oil will outstrip production of gas isn’t really relevant. In fact, if you’re using less oil as a result of the change in heating systems, and oil production is up, it’s possible that you can reduce your dependence on foreign oil without having to produce more oil than gas. A is out.

(B) Whether you are among the most dependent countries on foreign oil doesn’t matter. You are now, and we’re trying to determine if you will be in the future. This doesn’t help. Eliminate B.

(C) Hydroelectric, solar, and nuclear power aren’t relevant for this argument. We know that you’re dependent on foreign oil now, irrespective of other energy sources. It’s increased oil production and switching to gas that will, according to the argument, reduce this dependence. C is out of scope.

(D) Let’s say your oil consumption for electricity and transportation is increasing. Suddenly, the fact that you’re switching heating systems from oil to gas might not help – if your oil needs are going up in other areas, you may remain dependent on foreign oil. But if your oil consumption in these other areas is not increasing, that would reduce your dependence on foreign oil because your heating systems are switching to gas. D looks good.

(E) This doesn’t matter at all. We know that the systems are going to switch from oil to gas, so the question of whether some systems have already made the switch sheds no light on whether you will remain dependent on foreign oil.

D is the answer. Once you have the answer to whether your oil consumption for electricity and transportation is increasing, you’ll be better able to assess whether you will remain dependent on foreign oil, and, consequently, whether your reign as supreme ruler of Malvernia will continue.
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Malvernia
 
Step 1: Identify the Question

In the question stem, the words useful to establish in evaluating indicate that this is an Evaluate the Argument question.

Step 2: Deconstruct the Argument

Past: M lots I oil
Recent: heating oil → gas
Now: make > gas than use
oil prod incr steady
If trends cont → M rely less on foreign fuel

The conclusion is in the form of an if-then statement: If these trends continue, then something else will happen. It’s important to note that the author’s argument is predicated on the idea that the trends will continue. Don’t fall into a trap based on the possibility that the trends will NOT continue; the author hasn’t concluded anything about what might happen if the trends do not continue. The author is only claiming that her conclusion is true if M continues to produce more gas each year than it uses and if oil production keeps increasing at a steady pace.

What does this argument assume? M already has to import oil, but the argument assumes that increasing oil production at a steady pace will allow the country to reduce its oil imports. What if M’s oil consumption is increasing at a much greater pace than its oil production?

Step 3: Pause and State the Goal

On Evaluate questions, the answers will be in the form of a question or a “whether x is true” statement. The correct answer will address an issue on which the argument hinges, depending on whether that statement is true: one way, the argument will be strengthened; the other way, the argument will be weakened.

Step 4: Work from Wrong to Right

(A) The argument does not provide any detail about the relative amounts of oil vs. gas production. Whether M’s oil production outstrips gas production next year or in 20 years, it is still unclear whether the country needs more oil than it produces.
(B) The argument does not compare M to other countries. It is focused solely on whether M will continue to need to import foreign fuel.
(C) If 3% of M’s total needs are currently met by these other energy sources, nothing is changed about the current oil and gas needs as stated in the argument. If 50% of M’s total needs are currently met by these other energy sources, it is still the case that current oil and gas needs are the same as in the argument.
(D) CORRECT. If M needs an increasing amount of oil every year for other uses (electricity and transportation), then it may be the case that M’s oil production is not increasing at a fast enough rate to keep pace with demand. In this case, the argument is weakened. If, on the other hand, M does not need an increasing amount of oil every year for these other needs, then it may be the case that M’s oil production is increasing at a fast enough rate to keep pace with demand, in which case the argument is strengthened.
(E) If none have already been converted, the argument is not impacted because the conclusion is claimed to happen soon; the argument does not say that the conclusion has already occurred. If 1,000 have already been converted, the argument is still not impacted, because the conclusion is still set in the future.
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Dear GMATNinja,

I am unsure of what is given in the argument.

Is it given that the supply of natural gas will always be higher than the demand of natural gas?

So, we don't have to worry about the supply/demand of natural gas at all?

Thank you in advance sir!

The passage tells us that Malvernia currently produces more natural gas than it uses. We cannot infer from this that Malverrnia will always have an oversupply of natural gas -- maybe they will run out of natural gas stores, or maybe demand will greatly increase.

More to the point, we only have to "worry" about whether each answer choice can help us evaluate the argument. The only one that somewhat addresses the issue of supply/demand for natural gas is (A):

The issue with this answer choice is that we have no idea how much natural gas Malvernia actually produces -- supply is greater than demand, but what if both supply and demand are very small? Or, what if natural gas supply decreases, and oil production comes out ahead simply by remaining static?

(A) won't help us evaluate whether "Malvernian reliance on foreign sources for fuel is likely to decline soon," so (A) is not the correct answer.

I hope that helps!
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GMATNinja AjiteshArun VeritasKarishma,

I chose option 'E', can you please help me in understanding the flaw in my reasoning.
I used 'Malvernia recently implemented a program to convert heating systems from oil to natural gas.' and option 'E' to arrive at the logic that,

As of now, only a program has been implemented and if after converting the heating systems, to natural gas-based from oil-based, it's found that the converted systems are not even running and that they need to switch back to oil-based system their plan to reduce their reliance on foreign oil will fail.


Thanks
Saurabh

In the past Malvernia has relied heavily on imported oil.
Malvernia recently implemented a program to convert heating systems from oil to natural gas.
Malvernia currently produces more natural gas each year than it uses,
Oil production in Malvernian is increasing at a steady pace.

Conclusion: If these trends in fuel production and usage continue, Malvernian reliance on foreign sources for fuel is likely to decline soon.

Malvernia is converting heating systems from oil to gas. It has extra gas and is producing more oil every year. The conclusion is that if these trends continue, Malvernian reliance on foreign fuel will decrease.

Note that we are saying that supply of oil is increasing and gas is already extra. So converting heating systems to gas will reduce the demand of oil. So reliance on foreign oil will decrease. But what if oil demand increases due to other uses such as electricity generation and fuel. If the demand increases more than the supply, Malvernian reliance on foreign fuel may not decrease at all and may actually increase. This is what option (D) says.

As for (E), it doesn't matter whether any heating system has been converted yet. The program has been implemented recently. Perhaps it takes time to convert so no system has been converted yet. They may get converted in a while. Note that I understand your issue - do people actually execute the conversion. Had the question been something like - are people likely to execute as per the program? - that might be more relevant. But the question in (E) is whether any conversions have taken place yet. That is not relevant.

GMATNinja
VeritasKarishma
I have some questions with D choice.
it is a evaluation question.
So, if D IS, the argument is weakened.
if D ISN'T, the artument ISN'T strengthen.
even if the amount of oil used for generating electricity and fuel for transportation isn't change, it may have other source that will cost more oil.
D just refer to only 2 methods which will use oil, and there are obviously many other ways which will cost oil, right?
if D isn't, it doesn't mean the amount of oil used for other ways won't change, right?

I want to know whether D is right answer, thanks a lot.

Yup, (D) is definitely the right answer! The reasons for choosing (D) are explained in this post, as well as this one.

In addition, it is important to look at the exact language of the question:

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

Our task isn't to prove whether the argument is valid -- our task is just to find which statement would be most useful in evaluating the argument. So, even if (D) doesn't cover every possible use of oil (e.g., producing plastics), it would still be useful to know whether the amount of oil used each year for transportation and electricity is increasing. None of the other answer choices are useful at all, so (D) is the correct answer.

I hope that helps!
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If the consumption of oil increases, doesn't this contradict the premise
"If these trends in fuel production and usage continue".

The argument already says that current usage continues ..This is the sole reason I rejected D.
Can somebody please explain this?

Posted from my mobile device

The argument says "if THESE trends in fuel production and usage continue."

So according to the passage, which trends are THESE trends?

• Heating systems are converted from oil to natural gas
• More natural gas is produced domestically each year than is used domestically
• Domestic oil production is increasing at a steady pace

The only usage trend stated here refers to the energy source for heating systems.

Choice (D) asks, "Is the amount of oil used each year in Malvernia for generating electricity and fuel for transportation increasing?"

This question introduces additional data points on usage: the amount of oil used each year for generating electricity and for transportation.

This does not contradict or supersede information in the passage. In fact, answering this question would lead to valuable insight that would be very helpful in evaluating the conclusion (that reliance on foreign sources for fuel is likely to decline soon).

I hope this helps!
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This passage basically suggests that in Malvernia, there's a surplus of locally produced natural gas, but clearly a shortage of locally produced oil, although Malvernian oil production is increasing at a steady pace (we just don't know by how much). The conclusion "Malvernian reliance on foreign sources for fuel is likely to decline soon" is only valid if we know that any one or a combination of these trends is possible.

- Malvernian oil production is rising sharp enough to reduce Malvernia's reliance on imported oil, even if Malvernian reliance on oil as an energy source is increasing
- Malvernia's reliance on oil as a fuel declines sharply as a significant proportion of the country's energy mix transitions to locally produced fuel sources e.g. natural gas, and the natural gas surpluss is sufficient to meet this demand.


(A) - Incorrect: Irrelevant. We don't need Malvernian oil production to outstrip production of natural gas for Malvernia's reliance on imports to decline.

(B) - Incorrect: Irrelevant. Whether or not Malvernia is among the countries that rely the most on imported oil is irrelevant to whether Malvernia's reliance on imports will decline. It could be the most reliant or the least reliant - neither scenarios changes anything.

(C) - Incorrect: Out of scope. We don't necessarily need to know about the proportion of Malvernia's energy needs that are met by other fuel sources unless there's another trend that is occurring for another fuel source (e.g. energy supply from nuclear sources is rising fast enough to cope with Malvernian demand soon) but we don't have this information.

(D) - Correct - If Malvernia's reliance on oil is increasing, then it's unlikely that Malvernai's reliance on oil will decline soon. Even if Malvernian oil production is increasing at the same pace, Malvernia will continue to rely on imports to meet demand. If however, Malvernia's reliance on oil is not increasing, then we may expect to see a decline in Malvernia's reliance on foreign sources.

(E) - Incorrect: Warp. Even if some existing oil-burning heating systems have been converted to natural-gas-burning heating systems, Malvernia's reliance on foreign sources for fuel could still remain or increase. Heating systems are just one of several forms of uses of oil. We don't know the proportion of energy consumption that attributed to heating systems. Moreover, we don't have any information on those heating systems that have been converted as a proportion of all Malvernian heating systems.