An LSAT Critical Reasoning Problem

GRE Verbal Problem Solving
1

The following problem is from the Official LSAT PrepTest 2007.

image
image529×583 114 KB

It seems like a Math Problem. I broke down the problem as follows.
Conclusion: M group cans (new) = 2* L group cans (old)
Support: All cans recycled; no other material besides Aluminum (don’t know how it supports)
Fact: "50% of Aluminum in M came from L’

  • E is off-topic
  • D contradicts the information in the passage.
  • C looks good. But I am unable to relate it to the passage.Undecided
  • B also look good because if "50% of Aluminum in M came from L’ and M group cans (new) = 2* L group cans (old), it could be that they have reduced the quality of cans for the new cans. However, the passages says that all cans are “standard”. Therefore, undecided.
  • A is off-topic

Correct Answer is C. But how?

2

You’ve done a great job eliminating answers for being off topic, so take a closer look at B. Does the passage talk about “poorer quality” in recycled vs unrecycled cans? I think Greg would see “quality” as a sign that this is an off topic answer choice.

It also helps to think about what would weaken this argument as well. If 100% of the aluminum cannot be recycled, then the equation you set up would be false. Answer C ensures that your equation would be valid, and therefore the conclusion of the prompt.

3

Thanks.

Good point

Makes sense though I am not 100 percent satisfied.

4

Option B is also wrong if we consider this line

from the passage : “the amount of material other than aluminum in an aluminum can is negligible”