The conventional process for tanning leather uses large

Question

The conventional process for tanning leather uses large amounts of calcium oxide and sodium sulfide. Tanning leather using biological catalysts costs about the same as using these conventional chemicals if the cost of waste disposal is left out of the comparison. However, nearly 20 percent less waste is produced with biological catalysts, and waste disposal is a substantial part of the overall cost of tanning. It is therefore less costly to tan leather if biological catalysts are used instead.

Which one of the following is an assumption required by the argument?

(A) Leather tanned using the conventional process is not lower in quality than is leather tanned using biological catalysts.
 
(B) The biological catalysts that can be used in the tanning process are less costly by weight than are calcium oxide and sodium sulfide.

(C) New technological innovations have recently made the use of biological catalysts in the tanning process much more cost effective.

(D) Disposal of tanning waste produced with biological catalysts does not cost significantly more than disposal of the same amount of waste produced with the conventional process.

(E) The labor costs associated with tanning leather using biological catalysts are not any greater than the labor costs associated with the conventional tanning process.

Source: LSAT

MacFauz · Accepted Answer

Premise 1 : Conventional and biological catalyst methods cost the same if cost of waste disposal is not considered.
Premise 2 : Biological methods produce 20% less waste.

Conclusion : Biological method is cheaper.

Obvious jump : The cost per unit for disposal of the wastage may be different and can thus make the disposal of waste from the biological method more expensive.

(A) Leather tanned using the conventional process is not lower in quality than is leather tanned using biological catalysts.   Irrelevant. We are only concerned about the cost and not the quality of the leather.

(B) The biological catalysts that can be used in the tanning process are less costly by weight than are calcium oxide and sodium sulfide.    Irrelevant. Regardless of the cost of the catalysts, the fact that the methods cost the same is given in the premise itself.

(C) New technological innovations have recently made the use of biological catalysts in the tanning process much more cost effective.    Irrelevant. Again, the method still costs the same as conventional methods. It may only be more cost effective than it was previously but still costs the same as conventional methods.

(D) Disposal of tanning waste produced with biological catalysts does not cost significantly more than disposal of the same amount of waste produced with the conventional process.   Hits the nail on the head. This assumption assures us that the cost of disposing waste produced from the biological method is not much more expensive than the cost of removing the waste from conventional method. This is the answer.

(E) The labor costs associated with tanning leather using biological catalysts are not any greater than the labor costs associated with the conventional tanning process.    Irrelevant. Regardless of the cost of the labor, the fact that the methods cost the same is given in the premise itself.

lMarial · Answer

Thanks, it's clear.
I guess, this one is from LSAT, but i'm not sure.

akela · Answer

The conventional process for tanning leather uses large amounts of calcium oxide and sodium sulfide. Tanning leather using biological catalysts costs about the same as using these conventional chemicals if the cost of waste disposal is left out of the comparison. However, nearly 20 percent less waste is produced with biological catalysts, and waste disposal is a substantial part of the overall cost of tanning. It is therefore less costly to tan leather if biological catalysts are used instead.

Which one of the following is an assumption required by the argument?

(A) Leather tanned using the conventional process is not lower in quality than is leather tanned using biological catalysts.
(B) The biological catalysts that can be used in the tanning process are less costly by weight than are calcium oxide and sodium sulfide.
(C) New technological innovations have recently made the use of biological catalysts in the tanning process much more cost effective. 
(D) Disposal of tanning waste produced with biological catalysts does not cost significantly more than disposal of the same amount of waste produced with the conventional process.
(E) The labor costs associated with tanning leather using biological catalysts are not any greater than the labor costs associated with the conventional tanning process.

Source: LSAT

nightblade354 · Answer

Bumping for discussion. An easier LSAT question

David nguyen · Answer

The conventional process for tanning leather uses large amounts of calcium oxide and sodium sulfide. Tanning leather using biological catalysts costs about the same as using these conventional chemicals if the cost of waste disposal is left out of the comparison. However, nearly 20 percent less waste is produced with biological catalysts, and waste disposal is a substantial part of the overall cost of tanning. It is therefore less costly to tan leather if biological catalysts are used instead.

20% less waste -> Less costly

This is a big jump from premise to conclusion. Premise indicates % of waste, while Conclusion concludes less cost. We must justify this in order for the conclusion to be properly drawn.

Which one of the following is an assumption required by the argument?

Quality does not matter here. (A) is out
 
This only justify one side of the the issue. What about the amount of waste? (B) is out.
 
This is similar to (B). Yes, It is more cost effective but would the total cost still be higher? (C) is out.
 
This bridges our GAP. Hang on to this.
 
Labor cost is just a small part of the issue. The reasoning is concerned with total cost on the grounds that less weight leading to less cost. (E) is out.

(D) is the only one left. (D) is our answer.

mimishyu · Answer

(1)
tan leather Conventicoonal process use large amount of cal&sod
(2)
Biological catalysts cost the same=Conventional process
 if not consider the cost of Waste Dispposal(if we take Waste Disposal into account, the cost won’t be 
 the same)
(3)
however, Biological catalysts produce less Waste Disposal
Waste Dispposal is a substantial part of the overall cost of tanning
(4)
Conclusion
therefore, tan leather by using Biological catalysts is less costly
now we had to choose which one is the assumption, or say missing point in connecting those premises to conclusion

negation test: to check, if by negating (A)-(E), which one will let the conclusion/argument fall

(A) Leather tanned using the conventional process is not lower in quality than is leather tanned using biological catalysts.

Conventional process is “lower” in quality than Bio, but how will quality connect to cost, thus this won’t affect the conclusion

(B) The biological catalysts that can be used in the tanning
process are less costly by weight than are calcium oxide and sodium sulfide.

Bios used in tanning are “equal or more” costly by WEIGHT than the materials used in Conventional process
if we ignore the word “WEIGHT”, it seems this one be a plausible choice in that Bios be more costly than Conventional process and thus the conclusion breaks 
however, if take “WEIGHT” , a word totally irrelevant in our argument, into account, this just can’t be our choice

(C) New technological innovations have recently made the use of 
biological catalysts in the tanning process much more cost effective.

new innovation made Bios less cost effective- Bios cost more, but “innovation” doesn’t an issue in our argument

(D) Disposal of tanning waste produced with biological catalysts does not cost significantly more than disposal of the same amount of waste produced with the conventional process.

“DISPOSAL” produce with Bios does cost more than “DISPOSAL” with Convention-disposal of Bios cost more, best fit to the choice, as we already know that “DISPOSAL” be the main concern to our cost in process as well as our argument

(E) The labor costs associated with tanning leather using biological catalysts are not any greater than the labor costs associated with the conventional tanning process.

Same as (B) and (C), here labor cost doesn’t be a concern in our argument

KeyurJoshi · Answer

Conventional:
Waste produced = 100 kg
Waste disposal cost = $50 / kg
Total waste disposal cost = $5000
Method cost = $1000
Total = $6000

Biocatalyst:
Waste produced = 80 kg
Waste disposal cost = $50 / kg
Total waste disposal cost = $4000
Method cost = $1000
Total = $5000

Conclusion: Biocatalyst is less costly than conventional.

Which one of the following is an assumption required by the argument?

(A) Leather tanned using the conventional process is not lower in quality than is leather tanned using biological catalysts. =   Leather quality is OUT OF SCOPE. 
 
Negate (B)
(B) The biological catalysts that can be used in the tanning process are  NOT  less costly(equal/more costly) by weight than are calcium oxide and sodium sulfide. 
  Going back to what we have assumed, the method cost of both of them are same ($1000), so even if this is true our conclusion still stands and we don't know if BC cost is more than conventional chemicals. 
  
(C) New technological innovations have recently made the use of biological catalysts in the tanning process much more cost effective. =   This is irrelevant since we don't know the cost-effectiveness compared to the conventional chemicals.

Negate (D)
(D) Disposal of tanning waste produced with biological catalysts  COSTS  significantly more than disposal of the same amount of waste produced with the conventional process. 
 Consider the following example, 
Conventional:
Waste produced = 100 kg
Waste disposal cost = $50 / kg
Total waste disposal cost = $5000
Method (using conventional chemicals) cost = $1000
Total = $6000

Biocatalyst:
Waste produced = 80 kg
Waste disposal cost = $100 / kg
Total waste disposal cost = $8000
Method (using BC) cost = $1000
Total = $9000
 Here we can clearly see that BC cost (9000$) > Conventional method cost ($6000), conclusion does NOT stand.    CORRECT.

Negate (E)
(E) The labor costs associated with tanning leather using biological catalysts  ARE GREATER  than the labor costs associated with the conventional tanning process. =   The argument is specific to cost of chemicals used in tanning process and comparative waste disposal costs. If labor costs are excluded, the process using biocatalyst can still be less costly than using conventional chemicals .

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The conventional process for tanning leather uses large

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