Mexico City has a serious water problem. Situated in a high, enclosed

Question

Mexico City has a serious water problem. Situated in a high, enclosed mountain bowl, the city relies on groundwater for more than 80 percent of its supply. Pumping exceeds natural replenishment, so the depleted ground is subsiding, causing damage to buildings. Much water is lost to users, however, through leaks in the aging water-distribution system. Repairs would therefore increase the available supply without the damage that increased pumping would cause.

Which of the following, if true, is a consideration that weakens the argument given?

A) At some locations in the city, water use is not metered and cannot be billed to individual households.
B) The city has an extensive program of providing household water-saving devices at no direct cost to households.
C) Bringing water to the city from the nearest river, 80 miles away beyond the mountains, is extremely costly.
D) Water demand per person is falling, but migration is increasing the number of people in the city.
E) Water leaked from the water-distribution system seeps down, reaching the level of the groundwater.

MartyMurray · Accepted Answer

Mexico City has a serious water problem. Situated in a high, enclosed mountain bowl, the city relies on groundwater for more than 80 percent of its supply. Pumping exceeds natural replenishment, so the depleted ground is subsiding, causing damage to buildings. Much water is lost to users, however, through leaks in the aging water-distribution system. Repairs would therefore increase the available supply without the damage that increased pumping would cause.

The conclusion of the argument is the following:

Repairs would ... increase the available supply without the damage that increased pumping would cause.

The support for the conclusion is the following:

Much water is lost to users ... through leaks in the aging water-distribution system.

We see that the reasoning of the argument is that, because water is lost through leaks, through repairing the pipes, the water supply can be increased somewhat without damage to buildings.

Which of the following, if true, is a consideration that weakens the argument given?

This question is a Weaken question, and the correct answer will cast doubt on the conclusion.

A) At some locations in the city, water use is not metered and cannot be billed to individual households.

This choice indicates that there is an issue with the water system in Mexico city: in some areas, water use is not metered.

So, to avoid choosing this choice, we have to be careful to see that an issue with the water system as a whole is different from a problem with the plan of repairing leaking pipes to increase the supply of water without causing additional damage.

Since the fact that water use is not metered does not mean that the water supply won't be increased through repair of the pipes, this choice does not bring up a problem with the plan or weaken the argument.

Eliminate.

B) The city has an extensive program of providing household water-saving devices at no direct cost to households.

This choice indicates that something is already being done to address the water supply problem: provision of water-saving devices to households.

To avoid choosing this choice, we have to notice that the fact that something else is being done to address the problem does not mean that repairing the pipes won't help as well.

After all, both approaches could work at the same time, each approach helping to solve the water supply problem in its own way. In other words, even if water is being saved through the use of water-saving devices, repairing the pipes could still increase the supply.

Eliminate.

C) Bringing water to the city from the nearest river, 80 miles away beyond the mountains, is extremely costly.

This choice has no effect on the argument. After all, regardless of whether it's costly or not costly to bring water fron the nearest river, repairing the pipes could result in an increase in the water supply.

Eliminate.

D) Water demand per person is falling, but migration is increasing the number of people in the city.

This choice explains why so much water is being used: the number of people in the city is increasing.

At the same time, that fact does not weaken the argument. After all, regardless of how many people are using the water, repairing the pipes could result in increased supply without damage to buildings. Simply put, the fact that demand is increasing does not mean that supply cannot be increased through pipe repair.

Eliminate.

E) Water leaked from the water-distribution system seeps down, reaching the level of the groundwater.

This choice is interesting.

After all, if water leaked from the water-distribution system seeps down, reaching the level of the groundwater, then if the pipes are repaired, the supply will increase but not without damage to buildings.

After all, the water that's added to the supply through repair of the pipes would have reached and become part of the groundwater if it had continued to leak from the pipes. So, basically, the increase in supply would involve a decrease in the amount of groundwater, which, as the passage indicates, would lead to damage to buildings.

So, this choice indicates that increasing supply through repairing the pipes would likely lead to damage to buildings, and thus casts doubt on the conclusion that repairs would increase the available supply without the damage that increased pumping would cause.

Keep.

Correct answer:  E

ashutosh_73 · Answer

KarishmaB   MartyMurray

I got this one correct using POE, but i am still not convinced how ''E'' weakens the argument. This one came in Official mock-5.

Below is my understanding:

So my anti-conclusion is:  Even with repairs, you would  NOT  be able to increase the supply without the INCREASED PUMPING DAMAGE.

Does (E) weaken because: immediately after the REPAIR, you will have to replenish the full supply for ONE-TIME with the INCREASED PUMPING? 
Else, i can't see how (E) weakens the argument.

sayan640 · Answer

MartyMurray   KarishmaB  ,Request you to check my reasoning and correct me if I am wrong.
The conclusion of the argument:- The repair will be helpful in increasing the water supply.
Option E says that there is no harm being made by the leakage as the ground water is being replenished .
Hence there is no significant benefit that is possible by repairing .
They can go for the repairing but it's not gonna help much as the water leaked is already going back to the ground water level.
E is the answer as it will lead to the conclusion i.e "repairing will not be helpful ".

Posted from my mobile device

MartyMurray · Answer

That basically makes sense. It might be a bit better if you captured more specifically the conclusion, which is not simply that the repairs will be helpful but that repairing the pipes will increase supply without causing damage.

sayan640 · Answer

Thanks a lot  marty  Sir for validating...

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Mexico City has a serious water problem. Situated in a high, enclosed

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Mexico City has a serious water problem. Situated in a high, enclosed

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