Twenty years ago, Balzania put in place regulations requiring operator

Question

Twenty years ago, Balzania put in place regulations requiring operators of surface mines to pay for the reclamation of mined-out land. Since then, reclamation technology has not improved. Yet, the average reclamation cost for a surface coal mine being reclaimed today is only four dollars per ton of coal that the mine produced, less than half what it cost to reclaim surface mines in the years immediately after the regulations took effect.

Which of the following, if true, most helps to account for the drop in reclamation costs described?

A. Even after Balzania began requiring surface mine operators to pay reclamation costs, coal mines in Balzania continued to be less expensive to operate than coal mines in almost any other country.

B. Even after Balzania began requiring surface mine operators to pay reclamation costs, surface mines continued to produce coal at a lower total cost than underground mines.

C. As compared to 20 years ago, a greater percentage of the coal mined in Balzania today comes from surface mines.

D. Over the last 20 years, mine operators have generally located new surface coal mines in areas with flat terrain that makes reclamation easy.

E. In the 20 years since the regulations took effect, the use of coal as a fuel has declined from the level it was at in the previous 20 years.

MartyMurray · Answer

Twenty years ago, Balzania put in place regulations requiring operators of surface mines to pay for the reclamation of mined-out land. Since then, reclamation technology has not improved. Yet, the average reclamation cost for a surface coal mine being reclaimed today is only four dollars per ton of coal that the mine produced, less than half what it cost to reclaim surface mines in the years immediately after the regulations took effect.

Which of the following, if true, most helps to account for the drop in reclamation costs described?

Key to getting a Paradox question correct is correctly identifying exactly what the correct answer has to explain.

So, in this case, we have to be clear that the correct answer must explain why reclamation costs decreased despite the fact that reclamation technology has not improved.

A. Even after Balzania began requiring surface mine operators to pay reclamation costs, coal mines in Balzania continued to be less expensive to operate than coal mines in almost any other country.

This comparison of costs does not explain why costs decreased.

Eliminate.

B. Even after Balzania began requiring surface mine operators to pay reclamation costs, surface mines continued to produce coal at a lower total cost than underground mines.

This choice merely says that costs were relatively low without explaining why they decreased.

Eliminate.

C. As compared to 20 years ago, a greater percentage of the coal mined in Balzania today comes from surface mines.

This choice is tricky because it may seem to indicate that there was some kind of economy of scale that resulted in the cost decrease.

However, we don't have a clear reason to believe that such a dynamic existed. So, this choice doesn't really explain the cost decrease.

Eliminate.

D. Over the last 20 years, mine operators have generally located new surface coal mines in areas with flat terrain that makes reclamation easy.

This choice is interesting.

After all if this is true, the reclamation may have become easier since the regulations were put into place 20 years ago.

What's easier costs less.

So, this choice could explain why reclamation costs have decreased.

Keep.

E. In the 20 years since the regulations took effect, the use of coal as a fuel has declined from the level it was at in the previous 20 years.

The fact that use of coal has declined might explain a decrease in the price of coal, but it wouldn't explain a decrease in costs of reclamation of mined-out land.

Eliminate.

Correct answer:   D

Bunuel · Answer

Similar question to practrice: https://gmatclub.com/forum/twenty-years ... 30755.html

guddo · Answer

Twenty years ago, Balzania put in place regulations requiring operators of surface mines to pay for the reclamation of mined-out land. Since then, reclamation technology has not improved. Yet, the average reclamation cost for a surface coal mine being reclaimed today is only four dollars per ton of coal that the mine produced, less than half what it cost to reclaim surface mines in the years immediately after the regulations took effect.
 
 Which of the following, if true, most helps to account for the drop in reclamation costs described?

The puzzle is that reclamation costs have fallen even though reclamation technology has not improved.  So we need another reason  why mines reclaimed today are easier or cheaper to reclaim than mines reclaimed earlier.

A. Even after Balzania began requiring surface mine operators to pay reclamation costs, coal mines in Balzania continued to be less expensive to operate than coal mines in almost any other country.

This does not explain the drop in reclamation costs. It compares operating costs across countries, not reclamation costs over time.

B. Even after Balzania began requiring surface mine operators to pay reclamation costs, surface mines continued to produce coal at a lower total cost than underground mines.

This does not explain why surface-mine reclamation became cheaper. It compares surface mines with underground mines.

C. As compared to 20 years ago, a greater percentage of the coal mined in Balzania today comes from surface mines.

This does not explain the lower reclamation cost per ton. More coal coming from surface mines does not show that each reclaimed surface mine is cheaper to restore.

D. Over the last 20 years, mine operators have generally located new surface coal mines in areas with flat terrain that makes reclamation easy.

This is correct. If newer mines are in flat areas that are easier to reclaim, then the cost of reclaiming mines today could be much lower even without improved technology. This directly explains the  drop in reclamation cost .

E. In the 20 years since the regulations took effect, the use of coal as a fuel has declined from the level it was at in the previous 20 years.

This does not explain why reclaiming a surface mine now costs less per ton than before.

Answer: (D)

Gilmore · Answer

Hello,
I chose Option C because I interpreted it as suggesting that economies of scale reduced the average reclamation cost per ton of coal mined. However, I realise this explanation may rely on multiple assumptions that are not explicitly supported by the passage.
I’m struggling to understand why Option D is considered the correct answer.
The passage clearly states that reclamation technology has not improved. I interpreted this to mean that factors like the amount of land reclaimed per machine or the time required for reclamation have not changed significantly.
With Option D, are we supposed to assume that locating mines in flatter terrain makes reclamation easier and therefore reduces the cost per ton, even without improvements in technology?
In other words, does D explain the cost reduction by changing the conditions of reclamation (terrain) rather than the efficiency of the technology itself? Is it time reduction , leading to more reclaimed land per machine?
I’d appreciate clarification on how to correctly interpret this.

guddo · Answer

Yes, D explains the cost drop by changing the conditions of reclamation, not by improving the technology.

“Technology has not improved” only means the tools/methods are not better. But the same tools can still be cheaper to use if the land is easier to reclaim. Flat terrain may require less reshaping, less stabilization, less labor, and less time. So  easier terrain can reduce cost even with unchanged technology .

C is weaker because “a greater percentage of coal comes from surface mines” does not show that reclamation became easier or cheaper per ton. The economy-of-scale idea is possible, but it is an extra assumption not given in the option.

So D directly explains the cost decrease through  easier reclamation conditions .

SwethaReddyL · Answer

Twenty years ago, Balzania put in place regulations requiring operators of surface mines to pay for the reclamation of mined-out land. Since then, reclamation technology has not improved. Yet, the average reclamation cost for a surface coal mine being reclaimed today is only four dollars per ton of coal that the mine produced, less than half what it cost to reclaim surface mines in the years immediately after the regulations took effect.

Paradox - we need to find a reason on why the reclamation costs reduced compared to 20 years ago. For those who struggled on the term reclamation, it means the miners are paying for damage that is done.
 
 Which of the following, if true, most helps to account for the drop in reclamation costs described?

A. Even after Balzania began requiring surface mine operators to pay reclamation costs, coal mines in Balzania continued to be less expensive to operate than coal mines in almost any other country. - this operation of coal mines here and in any other country is an irrelevant comparison - OUT

B. Even after Balzania began requiring surface mine operators to pay reclamation costs, surface mines continued to produce coal at a lower total cost than underground mines. - this also talks about the total cost - OUT

C. As compared to 20 years ago, a greater percentage of the coal mined in Balzania today comes from surface mines - if greater percentage of coal mined comes from surface mines, why did the cost DECREASE? Even if it doesn't increase, it should atleast be the same right? - OUT

D. Over the last 20 years, mine operators have generally located new surface coal mines in areas with flat terrain that makes reclamation easy - now this gives us a reason to connect the reduced reclamation cost. If the mine operators located new surface coal mines that makes reclamation easy, then yeah, cost reduction makes sense - IN

E. In the 20 years since the regulations took effect, the use of coal as a fuel has declined from the level it was at in the previous 20 years - the usage of coal doesn't say much about the reduced reclamation costs - OUT

Option D, it is. The real struggle in this question is to connect the reclamation costs to the actual reduction reason without falling into the trap of picking choices that says total costs of coal or the usage of coal.

Thanks, 
 Swetha

egmat · Answer

Hi Gilmore,

Your own read of D at the end is actually spot-on, so let me confirm it and then untangle why C falls short.

First, what the correct answer must do.  The paradox is: reclamation  technology has not improved , yet cost per ton dropped by more than half. So we need a reason costs fell that does  not  depend on better technology. You nailed exactly this distinction in your last line.

Why D works.  D doesn't touch the efficiency of the technology at all. It changes  what is being reclaimed . Newer mines sit on "flat terrain that makes reclamation easy" - and easier land is cheaper to restore, no matter how good or bad the machines are. So the cost can drop even with the same old technology. That's precisely the mechanism the puzzle needs:  same tools, easier job . You don't have to assume anything about time-per-machine or land-per-machine - the choice hands you "easy" directly.

Why C doesn't.  C says a greater  percentage  of coal now comes from surface mines. To turn that into lower reclamation cost per ton, you have to  add  a premise - that more surface mining created economies of scale that cut per-ton reclamation cost. The stimulus never gives you that link. Notice the contrast: D states its mechanism outright ("makes reclamation easy"), while C only works if  you  supply the missing chain. In CR, the answer that needs you to import an unstated assumption loses to the one that spells the cause out.

Quick gut-check to lock it in.  Imagine the same paradox about house-painting: "Our paint hasn't improved, yet our cost per house has halved."

- "We now paint a bigger share of all the town's houses." - Does that explain it? Only if you  assume  scale savings.
- "We now mostly paint small, single-story houses." - That explains it instantly: easier job, lower cost.

Same move as D. You were already seeing it correctly - trust that instinct.

Answer: D

Twenty years ago, Balzania put in place regulations requiring operator

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

GMAT Critical Reasoning (CR) Questions

Twenty years ago, Balzania put in place regulations requiring operator

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards