From 1978 to 1988, beverage containers accounted for

[nayak.purnendu]

From 1978 to 1988, beverage containers accounted for a steadily decreasing percentage of the total weight of household garbage in the United States. The increasingly widespread practice of recycling aluminum and glass was responsible for most of this decline. However, although aluminum recycling was more widely practiced in this period than glass recycling, it was found that the weight of glass bottles in household garbage declined by a greater percentage than the weight of aluminum cans.

Which of the following, if true of the United States in the period 1978 to 1988, most helps to account for the finding?

(A) Glass bottles are significantly heavier than aluminum cans of comparable size.
(B) Recycled aluminum cans were almost all beverage containers, but a significant fraction of the recycled glass bottles had contained products other than beverages.
(C) Manufacturers replaced many glass bottles, but few aluminum cans, with plastic containers.
(D) The total weight of glass bottles purchased by households increased at a slightly faster rate than the total weight of aluminum cans.
(E) In many areas, glass bottles had to be sorted by color of the glass before being recycled, whereas aluminum cans required no sorting.

GmatPrep:
Tutors please help me in cracking this question.
I marked D. OA:C
The passage was concerned with "WEIGHTS" - then how come C is correct?
C was a contender as glass bottles it states the NUMBER of glass bottles in household garbage decreased more significantly than aluminum cans. But will that mean weight also decreases with this change ???

[rohit21384]

From 1978 to 1988, beverage containers accounted for a steadily decreasing percentage of the total weight of household garbage in the United States. The increasingly widespread practice of recycling aluminum and glass was responsible for most of this decline. However, although aluminum recycling was more widely practiced in this period than glass recycling, it was found that the weight of glass bottles in household garbage declined by a greater percentage than the weight of aluminum cans.

Which of the following, if true of the United States in the period 1978 to 1988, most helps to account for the finding?

(A) Glass bottles are significantly heavier than aluminum cans of comparable size.
(B) Recycled aluminum cans were almost all beverage containers, but a significant fraction of the recycled glass bottles had contained products other than beverages.
(C) Manufacturers replaced many glass bottles, but few aluminum cans, with plastic containers.
(D) The total weight of glass bottles purchased by households increased at a slightly faster rate than the total weight of aluminum cans.
(E) In many areas, glass bottles had to be sorted by color of the glass before being recycled, whereas aluminum cans required no sorting.

GmatPrep:
Tutors please help me in cracking this question.
I marked D. OA:C
The passage was concerned with "WEIGHTS" - then how come C is correct?
C was a contender as glass bottles it states the NUMBER of glass bottles in household garbage decreased more significantly than aluminum cans. But will that mean weight also decreases with this change ???

I got it...
At the start of the period:
Let us assume on a daily basis following units were used and disposed off (with 0 % recycling):
100 units of Glass bottles
and
100
units of Aluminium cans.

Option C:
Manufacturers replaced many glass bottles, but few aluminum cans, with plastic containers.

now following could be the usage :
50 units of glass bottles on daily basis (more (50)glass bottles were replaced with plastic)
and 90 units of Aluminium cans on daily basis.(less (10) glass bottles were replaced with plastic)


Since more aluminum cans are recycled than are glass bottles...
so let assume that 50 units of aluminium are recycled and 25 units of glass bottles are recycled on daily basis.

Consequently the amount disposed of would be:
Glass bottles : 50- 25 = 25 (fall of 75 % from 100 units)
Aluminium Can : 90- 50 = 40 (fall of 60 % from 100 units)

Hence the conclusion: glass bottles in household garbage declined by a greater percentage than aluminum cans.
So it supports the findings


Option D
The total weight of glass bottles purchased by households increased at a slightly faster rate than the total weight of aluminum cans.

Now assume the following:
Aluminium can daily usage : 110(10 % up from 100)
Glass bottles daily usage: 130 (30% up fom 100)

Since more aluminum cans are recycled than are glass bottles...
again let assume that 75units of aluminium is recycled and 50 units of glass bottles are recyled on daily basis.

Consequently the amount disposed of would be:
Glass bottles : 130- 50 = 80 (fall of 20% from 100 units)
Aluminium Can : 110- 75 = 35 (fall of 65 % from 100 units)

So glass bottles in household garbage declined by a less percentage than aluminum cans.
This result is contrary to the findings.

[rags99]

between C & D:

d : if we assume D is true, in what way will it impact the conclusion?
D talks abt purchase...Conclusion talks abt, drop in recycled glass.


c: If we assume C to be true, we can conclude: ppl were purchasing the same stuff , not in glass bottles but plastic bottles.

plastic replaced MANY glass...but FEW aluminium.

[RonPurewal]

From 1978 to 1988, beverage containers accounted for a steadily decreasing percentage of the total weight of household garbage in the United States. The increasingly widespread practice of recycling aluminum and glass was responsible for most of this decline. However, although aluminum recycling was more widely practiced in this period than glass recycling, it was found that the weight of glass bottles in household garbage declined by a greater percentage than the weight of aluminum cans.

Which of the following, if true of the United States in the period 1978 to 1988, most helps to account for the finding?

(A) Glass bottles are significantly heavier than aluminum cans of comparable size.
(B) Recycled aluminum cans were almost all beverage containers, but a significant fraction of the recycled glass bottles had contained products other than beverages.
(C) Manufacturers replaced many glass bottles, but few aluminum cans, with plastic containers.
(D) The total weight of glass bottles purchased by households increased at a slightly faster rate than the total weight of aluminum cans.
(E) In many areas, glass bottles had to be sorted by color of the glass before being recycled, whereas aluminum cans required no sorting.

GmatPrep:
Tutors please help me in cracking this question.
I marked D. OA:C
The passage was concerned with "WEIGHTS" - then how come C is correct?
C was a contender as glass bottles it states the NUMBER of glass bottles in household garbage decreased more significantly than aluminum cans. But will that mean weight also decreases with this change ???

this problem turns on the differences between PERCENTAGES and ABSOLUTE NUMBERS.

facts:
* the PERCENTAGE of recycled aluminum was higher than the PERCENTAGE of recycled glass. this is what it means when we say that aluminum recycling was more widely practiced.
BUT
* the NUMERICAL CHANGE in aluminum in the trash was lower than the NUMERICAL CHANGE in glass in the trash.

if all the stuff missing from the trash had been recycled, this would be impossible. therefore, we need another explanation, besides recycling, for WHY THE TOTAL USE OF GLASS HAS GONE DOWN. that's the only way that these findings are mathematically possible.

(c) is such a statement.

(d) is the EXACT OPPOSITE of this sort of statement. if (d) were true, we would expect to see aluminum, not glass, declining at a faster rate in the trash.

[madhavbatra]

Hi Can you please help me understand why A is incorrect?
If glass bottles are significantly heavier, it would result in a greater reduction in the weight vis a vis aluminum cans.

[tim]

sorry, absolute weight has no bearing on percentage decline. if the weight glass bottles in trash declined by 25%, similar circumstances would yield the same percentage decline regardless of the weight of each glass bottle..

[jibanezd]

what's wrong with A?
Thanks.

[RonPurewal]

what's wrong with A?
Thanks.

tim explained what's wrong with (a) in the post directly above yours. if you don't understand his explanation, please respond to it with a specific question.
thanks.

[facadeof_reality]

what's wrong with A?
Thanks.

tim explained what's wrong with (a) in the post directly above yours. if you don't understand his explanation, please respond to it with a specific question.
thanks.

Hi Ron,

My apologies but I'm still not able to understand why A is wrong.

My understanding was that if the weight of glass bottle is more than that of plastic can then the % decrease in weight will be more even though more number of plastics can are removed.

[RonPurewal]

My understanding was that if the weight of glass bottle is more than that of plastic can then the % decrease in weight will be more even though more number of plastics can are removed.

the problem quotes two separate percentages -- one percentage of the total weight of glass, and another percentage of the total weight of plastic. because these are separate percentages, it doesn't matter how much each thing weighs.

for instance, if a household uses half as many glass containers, then that's a 50% reduction, regardless of whether the glass containers weigh 2 ounces or 2 tons each.

if the problem were talking about the relative contributions of glass and plastic to the total weight of all recycled materials, then you would have a point here. however, the problem isn't talking about that.

[kartikdatwani]

Hi Ron

Please answer this query -

Isn't option D grammatically/logically wrong?
It compares rate of increase of weight of glass bottles to the weight of aluminium cans.

I eliminated this answer choice based on the above mentioned fact. How can rate be compared to actual weight?
Also, more importantly - Is it right to eliminate answer choices in CR
on the basis of their grammatical incorrectness?

Thanks.

[tim]

D is saying that the total weight of one thing increased faster than the total weight of another thing. We are comparing the rates of increase for these total weights. On CR you do not need to be so picky with the grammar, as long as you can make sense of what is intended by the sentence.

[NinaP494]

BUT
* the NUMERICAL CHANGE in aluminum in the trash was lower than the NUMERICAL CHANGE in glass in the trash.

Are you sure about this Ron?

The argument says "...it was found that the weight of glass bottles in household garbage declined by a greater percentage than the weight of aluminum cans."

This can happen even if the the NUMERICAL CHANGE in aluminum in the trash is the same as the NUMERICAL CHANGE in glass in the trash if we had less glass by weight to begin with.

What am I missing here?

[RonPurewal]

ok, well, maybe the problem is just the specific words that I used there.

the point is that...
• ... more aluminum than glass (percentage-wise) is being removed from the trash -- for recycling purposes,
BUT
• ... nevertheless, the weight of glass went down by a greater percentage.

these are clearly in conflict with each other, so, we need some other reason why the weight of glass went down -- above and beyond recycling.

[JbhB682]

Hi - Alternatively, can i eliminate D with the following logic (this was my reason for eliminating D)

D has nothing to do with the "WHY" the finding in red happened

It just happens to give us another fact but doesnt discuss the "WHY" (Qualitative reason for the finding in Red)

Thank you !
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From 1978 to 1988, beverage containers accounted for a steadily decreasing % of the total weight of household garbage in the United States. The increasingly widespread recycling of aluminum and glass was responsible for most of this decline. However, although aluminum recycling was more widely practiced than glass recycling, it was found that the weight of glass bottles in household garbage declined by a greater % than the weight of the aluminum cans.

Which of the following, if true of the United States in the period 1978 to 1988, most helps to account for the finding?

(A) Glass bottles are significantly heavier than aluminum cans of comparable size.

(B) Recycled aluminum cans were almost all beverage containers, but a significant fraction of the recycled glass bottles had contained products other than beverages.

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

(D) The total weight of glass bottles purchased by households increased at a slightly faster rate than the total weight of aluminum cans.

(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.