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Understanding the argument -
In these ten years - Beverage containers (BCs) accounted for a lower %age weight of household garbage. This means, say earlier, out of every 100 units of household garbage, we had 50 units of BCs, but in these years, for every 100 units, we only got ten units of BCs.
Why this happened - credit to recycling. Between the two kinds of BCs, the Aluminium (A) was recycled more than Glass Bottle (G). So what will you expect? In those ten units of garbage, we got, we would expect, say, more units of bottles and fewer units of Aluminium. Right? But the opposite of this has happened, and that is the paradox.

Just think in what scenario that'll happen. Maybe earlier, we made 20 units of Aluminum and 20 units of Glass bottles overall. Say now all manufacturers start using more Aluminium. Say now we make 38 units of Aluminium and two units of Glass. This is one possibility. Another possibility is that we use a different material altogether. Out of these 20 Aluminium cans, five are made of plastic, and the remaining 15 are aluminum, but for Glass bottles, out of 20, we now make 19 units out of plastic and 1 unit with glass. (So that you don't panic - think of 1 unit to be, for example, 1 million kilograms). Ultimately, we are trying to reduce the supply of glass bottles. This is what option C does.

Option Elimination -

(A) Glass bottles are significantly heavier than aluminum cans of comparable size. - When we compare %age - heaviness or lightness doesn't matter. Distortion.

(B) Recycled aluminum cans were almost all beverage containers, but a significant fraction of the recycled glass bottles had contained products other than beverages. The findings don't even talk about BCs or non-BCs. It just talks about Aluminium or Glass, whatever the contents may be. This is a classic distortion.

(C) Manufacturers replaced many glass bottles, but few aluminum cans, with plastic containers. - ok

(D) The total weight of glass bottles purchased by households increased at a slightly faster rate than the total weight of aluminum cans. - This worsens the paradox. Opposite of what we are looking for.

(E) In many areas, glass bottles had to be sorted by color of the glass before being recycled, whereas the aluminum cans required no sorting. - Sorting doesn't help resolve the paradox. Nowhere does it say that if sorting is more difficult, it means less of that content in the garbage. At best, this may worsen the paradox.
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KarishmaB pls explain why not A and how can it be disproved? The explanations provided are not solid for rejecting A
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Elite097
pls explain why not A and how can it be disproved? The explanations provided are not solid for rejecting A

I could be wrong, but may be this way?
The option doesnt really specify it, but I think its average weight in option A.

weight of total cans = no. of cans * average weight per can

the percentage change in total weight will be

(weight of new number of cans - weight of original number of cans)/( weight of original number of cans)

here average weight per can can be taken out as below and cancelled in numerator and denominator. So only number change contributes to percent change.

average weight per can (new no. of cans - no. of original cans) / average weight per can * no. of original cans
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Say we have 100 bottles, 50 GL, 50AL
AL gets recycled more according to " aluminum recycling was more widely practiced than glass recycling"
50 AL = 30 Recycled + 20 AL
50 GL = 10 recycled + 40 GL

However now they say Weight_GL < Weight_AL,

So A is def wrong, A should be the opposite in fact.

C says now 100 bottles = (10GL+40PL)+(30AL + 20PL)
which is a good explanation why W_GL < W_AL
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The first sentence says there is a decline in the percentage of beverage waste. But in answer choice C it says that glass has been changed to plastic, and we have no clue whether the plastic is recyclable or if it weighs the same. So without that knowledge the plastic still ends up in the trash and the weight will remain the same. Hence doesn't that violate the information given in the first sentence?
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I did not get the logic behind C option. It is already mentioned in the passage that Aluminium was more widely recycled than glass. Then saying that glass bottles were more recycled or replaced contradict what is already stated. If glass bottles are more replaced then it should be the most widely replaced object not the aluminium one.
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The question asks us to "account for a finding," so let's take a look at the exact "finding" in the passage:

There is a discrepancy between this finding and the fact that "aluminum recycling was more widely practiced than glass recycling." This fact would otherwise lead us to expect the weight of aluminum cans in the trash to decrease by a greater percentage than that of glass bottles, because cans that are recycled would not end up in the trash.

Our task is to find an answer choice that explains the discrepancy between the finding and the evidence. Let's go through the answer choices:


The finding in the passage deals with change in the percentage of weight of both items. Even if glass bottles are heavier than aluminum cans, you would still expect their weights to be reduced proportionally -- so if aluminum cans are recycled more, you would expect the weight of aluminum cans in the trash to decline more by percentage than the weight of glass bottles.

Answer choice (A) would be relevant in studying the change in total weight of these materials, but not so much for percent of weight. This factor does not explain the discrepancy in the change of percentage of weight. Answer (A) is out.


If you look back at the "finding" in the passage, it does not mention beverage containers at all. We are concerned only with the weight of glass bottles and aluminum cans in the trash by percentage. The contents of those glass and aluminum objects are irrelevant to the conclusion, so answer (B) is out.


This is more like it. We need a reason for a greater decline in percentage of glass bottles in the trash than aluminum cans in the trash, and answer (C) gives us a good reason. Households replaced "many" glass bottles with plastic containers, while only replacing "few" aluminum cans with plastic. So fewer glass bottles would end up in the trash despite more aluminum cans being recycled. This accounts for the discrepancy between the evidence and finding.

(C) is looking great, but let's finish up the other answer choices.


We are looking for a reason that the percentage of weight of glass is lower than expected when compared to that of aluminum. Answer (D) states that household purchases of glass bottles is increasing faster than purchases of aluminum. This is the opposite of what we need to resolve the discrepancy, so answer (D) is out.


This answer might explain why aluminum recycling is more widespread than glass recycling, but it has nothing to do with the central discrepancy we are trying to resolve: why did the percentage of weight of glass decrease more than that of aluminum?

Answer (E) is out, and answer (C) is correct.
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The passage says: "Aluminum recycling was more widely practiced" Option C says: "Glass replacement was more widespread"
These are two DIFFERENT things - not a contradiction!

Simple Comparison-
RECYCLING = Taking old bottles/cans → Processing them → Reusing the material
  • Aluminum wins here ✓
REPLACEMENT = Manufacturers stop making glass/aluminum containers → Switch to plastic instead
  • Glass wins here ✓

Both can be true at the same time

mkeshri185
I did not get the logic behind C option. It is already mentioned in the passage that Aluminium was more widely recycled than glass. Then saying that glass bottles were more recycled or replaced contradict what is already stated. If glass bottles are more replaced then it should be the most widely replaced object not the aluminium one.

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First, let's be clear about what "declined by a greater %" means:
We're comparing how much each type of container decreased relative to its own starting point.
For example:
  • If glass went from 1000 kg → 300 kg, that's a 70% decline (it lost 700 kg out of its original 1000 kg)
  • If aluminum went from 100 kg → 60 kg, that's a 40% decline (it lost 40 kg out of its original 100 kg)
  • Glass's 70% decline is bigger than aluminum's 40% decline
We're NOT just comparing total weights. We're comparing what percentage each one dropped from where it started.

Let me show you with simple numbers why A doesn't work:
In 1978:
  • Glass in garbage: 1000 kg
  • Aluminum in garbage: 100 kg (yes, it's lighter like A says)

By 1988, with only recycling happening:
The passage says aluminum is recycled MORE. So let's say:
  • Aluminum: 40% gets recycled → Goes from 100 kg down to 60 kg
  • Glass: Only 20% gets recycled → Goes from 1000 kg down to 800 kg

Calculate percentage drops:
  • Aluminum dropped by: (100 - 60) ÷ 100 = 40%
  • Glass dropped by: (1000 - 800) ÷ 1000 = 20%
Wait! Aluminum dropped MORE (40% vs 20%), not glass! Even though glass is heavier, aluminum still wins because way more aluminum got recycled. Option A doesn't fix our problem.

Now let's try Option C:
C says manufacturers switched from glass bottles to plastic bottles, but kept making aluminum cans.

By 1988:
  • Aluminum: 40% recycled → Goes from 100 kg to 60 kg (same as before)
  • Glass: 20% recycled → Would be 800 kg, BUT manufacturers also stopped making 500 kg worth of glass bottles (they made plastic instead) → So only 300 kg of glass ends up in garbage

Calculate percentage drops:
  • Aluminum: (100 - 60) ÷ 100 = 40%
  • Glass: (1000 - 300) ÷ 1000 = 70%

NOW glass dropped more! 70% is bigger than 40%.

Why C works and A doesn't: Glass being heavier doesn't help when less of it is being recycled. But glass being replaced by plastic means way less glass even enters people's homes. That's what pushes glass's percentage drop above aluminum's.

Elite097
KarishmaB pls explain why not A and how can it be disproved? The explanations provided are not solid for rejecting A
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