In the next decade, a large percentage of municipalities throughout

Dear Poorvasha,

I'm the author of this question and I'm happy to respond.

Here's the prompt:
In the next decade, a large percentage of municipalities throughout the country will experience power failures if they do not modernize their electrical substations. The vast majority of substations in the country already handle currents between 60% and 80% of their maximum capacity, and currents are expected to rise, perhaps by as much as a factor of 3 in the next decade, because of population increase and the increased demand from both industry and electronics in individual homes.

Which of the following is an assumption of the above argument?

Notice that the conclusion is in the the first sentence, and the second sentence is pure evidence. Also, notice that the argument strictly is about what will happen if municipalities "do not modernize their electrical substations." That means, what happens if and when they do "modernize their electrical substations," is, strictly speaking, irrelevant to the argument. The argument is about what will cause the current substations to fail.

We will use the Negation Test.

A) An electrical substation fails when the current it handles rises above its maximum capacity.
Suppose the opposite is true: when current rises about the maximum capacity, the electrical substation are fine and can still function as normal. This would obliterate the arguments. Essentially, the "maximum capacity" ratings would be meaningless, because electrical substation would function and not fail even above these levels. This destroys the argument. Because negating this destroys the argument, this is an assumption.

B) A modernized electric substation would be able to handle at least three times the amount of current as does a current substation.
This is a very tempting wrong answer. Notice, first of all, the argument about what will cause the current substations to fail--that's the focus, the main problem. Also, notice that the argument says that the expect rise will be "perhaps by as much as a factor of 3 in the next decade"--in other words, it's not certain that the electrical current demands will go this high. Whether the modernized electric substations can handle things or fail has no bearing on the current problem--in other words, the current substations are very likely to fail, regardless of what the modernized electric substations can or can't do. Also, we don't know for sure exactly how high the current needs will go. Suppose the modernized electric substations can't handle 3 times the current level, but can handle up to, say, 2.5 times the current level. Well, if current levels rise to a maximum of 2.3 times the current level, then the modernized electric substations would be able to handle that. Thus, this choice can be negated and the argument still works, so this isn't a true assumption.

(A) is right and is the OA. (B) is a very tempting incorrect answer.

Does all this make sense?
Mike
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Hi anupama,

As per B the modernised substation would be able to handle atleast 3 times the current. means greater than or equal to 3.

As per the para we see that its predicted that the current consumption might increase PERHAPS by AS MUCH AS a factor of three.

That means that its possible that it can be less than or equal to 3. Given that it is not necessary that the modernized substations be capable of handling that much current only.

Hence if you negate B and see the argument does not fall apart.

Hope its clear?

Regards,
Dom

Only A makes sense.

As per A: The substation will fail if the current exceeded the maximum capacity.

negate A: The substation will not fail if the current exceeded the maximum capacity.

If the negated A were acceptable there wont be any requirement to possibly upgrade the system firstly. Hence the argument will fall apart.

Hence A is the correct answer.

Regards,
Dom.

Could you please explain your thought process on this?
what is wrong with B
How A is correct?

I was stuck between A VS B

In the next decade, a large percentage of municipalities throughout the country will experience power failures if they do not modernize their electrical substations. The vast majority of substations in the country already handle currents between 60% and 80% of their maximum capacity, and currents are expected to rise, perhaps by as much as a factor of 3 in the next decade, because of population increase and the increased demand from both industry and electronics in individual homes.

Which of the following is an assumption of the above argument?

(A) An electrical substation fails when the current it handles rises above its maximum capacity.

(B) A modernized electric substation would be able to handle at least three times the amount of current as does a current substation.

(C) Ten years from now, the average household will own a greater number of electronic devices than does the average household today.

(D) Many electrical substations in operation today are old, and have several aged components that could break down, leading to power failures, even if current levels don't increase substantially.

(E) The cost of modernizing the substations is small compared to the average profits of electrical power companies.
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Topics merged. tuanquang269, please search for a question before starting a new thread.
Thanks,
Mike
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Hi mikemcgarry

Can you please help in explaining A vs B.

Thanks in advance

Thank you Mike. This was very helpful. . +1

Official Explanation

For an assumption, we can use the Negation Test. The credited answer is (A). Suppose (A) is false. Suppose an electrical substation is perfectly capable of handling currents well above its "maximum" capacity (it's unclear what "maximum" would mean in this instance, but we'll overlook that). If electrical substations can handle much more current, then even if current demands increase by a factor of three, that won't be a problem at all. Negating this statement devastates the argument, so this statement must be an assumption.

The argument is about current substations and whether they will fail. Facts about what new modern substations can handle are outside of the scope of this argument. Choice (B) is incorrect.

All we know is that the overall "demand from both industry and electronics in individual homes" will increase. Does this mean more demand from each house, or simply more houses with the same level of demand? And even if each house has more demand, does that mean they have more electronic devices, or simply a small number, each of which demands an intense amount of electrical power? There is too much we don't know, so choice (C) is incorrect.

Choice (D) could strengthen the argument if it were true, but if we negate it, this doesn't destroy argument. It's possible that the current substations are not that old, and would not break down at current levels, but still would fail at increased levels of demand. Since we can negate (D) and the argument could still work, this means (D) is not an assumption. Choice (D) is incorrect.

Choice (E) brings in irrelevant information about cost: how much it would or wouldn't cost to modernize the substations in operation now doesn't affect how likely it is that they will fail. Choice (E) is incorrect.



FAQ: Why is answer choice (B) incorrect? The conclusion says that there will be power failures if municipalities don't modernize their electrical substations. If we negate choice B, the power failures will occur - so (B) seems like a necessary assumption.

Answer choice (B) can definitely be an attractive option. The passage does say that the amount of electric current in power grids might rise by a factor of three in ten years and does say that "a large percentage of municipalities throughout the country will experience power failures if they do not modernize their electrical substations." So it might look like the argument falls apart if modern substations can't handle three times as much power as existing substations.

However, it's important to pay very close attention to the exact phrasing of the argument. Note that the argument says that "currents are expected to rise, perhaps by as much as a factor of 3 in the next decade." So it's actually not completely certain that the amount of current in power grids will be that high in ten years. And as a result, it might not be necessary that modern substation be able to handle three times as much current as existing substations.

Also, note that the argument concludes that a large number of municipalities need to "modernize their electrical substations." This sounds like "build modern substations" but is actually slightly different. One could, for instance, "modernize" an existing substation by modifying it to handle twice as much power as it could previously and still see at least some sort of improvement. So we don't need to install completely new substations to successfully modernize substations.

Basically, then, there is a bit of "wiggle room" in the phrasing of the argument that makes B not an absolutely vital assumption. However, if A ("An electrical substation fails when the current it handles rises above its maximum capacity.") is false, the argument does fail to work. If electrical substation doesn't fail when it goes over capacity, then there's much less of a reason to improve substations to handle the increasing levels of electrical current. So this is by far the best option to pick for this question.

I think A) can't be the assumption.
If we negate A we get: "An electrical substation doesn't fail when the current it handles rises above its maximum capacity."
so may be substation is able to handle 1.1 times its maximum capacity. But still, we would require the new modern substation because 1.1 times the maximum capacity wouldn't be sufficient to solve the crisis.
I believe that negation of A) doesn't really break the conclusion.
Can anyone help in providing flaw in my reasoning?

marvel3001

Above answers have already covered this part. just reiterating

Conclusion : a large percentage of municipalities throughout the country will experience power failures if they do not modernize their electrical substations.

Just by reading this part from premise one can say -- power failures if not modernize. Now this become a fact.

Suppose an electrical substation is perfectly capable of handling currents well above its "maximum" capacity (it's unclear what "maximum" would mean in this instance, but we'll overlook that). If electrical substations can handle much more current, then even if current demands increase by a factor of three, that won't be a problem at all. Negating this statement devastates the argument, so this statement must be an assumption.

A should be the best answer. Let me know if you have any doubt. I will be happy to help you.

mikemcgarry GMATNinja

2 doubts -
1)are power failures the same as power cuts?
2) the conclusion is if not X, then Y will happen ...now how do we interpret this?

Can I say even if X, then Y will not happen
Ie. Even if modernise we will face failures
OR
We will face failures if we don't modernise...

Where does author's confidence lie in?
Is it that if we don't do X, Y will definitely happen

OR

If we do X, Y will not happen

And if it's the former please explain to me why can't we interpret the latter (if we do X, Y will not happen...if we modernise, no power failures)

Posted from my mobile device

To simplify:

municipalities will experience power failures if they do not modernize their electrical substations which already handle currents between 60% and 80% of their maximum capacity since currents are expected to rise as much as a factor of 3

in order to achieve power failures,electrical substations must fail to handle rising currents

A) An electrical substation fails when the current it handles rises above its maximum capacity.

Great questions even more great are the options
and then there's mike and his expanations
Hats offf man.

Hi Mike can you explain for choice D
•The argument says for vast majority of substations and not for all substations, also current level are expected to rise as much as 3 times.
•Choice D also talks for many substations not all substations , and it also says several aged components could break down, leading to power failures, even if current levels don't increase substantially.
So even if current level increases by minimum factor substations will break down, right?
Therefore we may have to modernise these electrical substation.

This is my understanding of choice D
I got the reasoning of A but I'm not able to eliminate D.
I'll appreciate if you can spare some time on this mikemcgarry GMATNinja
Thanks

Just curious here, how is there a maximum capacity if actually the current can rise above the maximum capacity without the substation experiencing power failure? It’s like saying the volume of a cup is 3 litres but we can actually fit 5 litres if the premise doesn’t state otherwise.

Posted from my mobile device

mikemcgarry

think that is more of an inference type question

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