Errata List - 4th Edition 10 Real LSATs Grouped by Type

[ManhattanPrepLSAT1]

Post any typos/errors within this book here.

4th Edition Practice Book I: 10 Real LSATs Grouped by Type

[christine.defenbaugh]

We have discovered an error on p. 474 of the 4th Edition Practice Book I: 10 Real LSATs Grouped by Type.

The answer and explanation given for PrepTest 45, Section 1, Question 11 are incorrect. We have rewritten the explanation below! Please use this explanation instead of the one printed in the book.

Q11. (C)
Match the Flaw

Our first line of attack in Match the Flaw questions is to identify the flaw in the stimulus!

PREMISE: average cost of [groceries] will rise
CONCLUSION: cost of [subgroup: butter & eggs] will rise

This argument commits a version of a Part/Whole flaw. From the evidence that an entire group will, on average, behave a certain way, the author concludes that one subset of that group will behave that way. There is no guarantee that every subset of the larger group will behave the same way: perhaps the price of butter and eggs will decrease, but other the price of other groceries will increase enough that the average price still rises.

Answer choice (C) commits this same error.

PREMISE: average TV time for [people under 20] has increased
CONCLUSION: TV time for [subgroup: 4th graders] has increased

The author uses information about the average increase for a whole group to support a claim that a subset of that group has behaved the same way. Perhaps 4th graders have all been grounded from TV, but the high-school kids are watching so much TV that the average for the whole group is still increasing!

Note that the stimulus makes a prediction about the future, while the correct parallel answer makes a claim about the past. That's okay, because each argument stays consistent between the premise and the conclusion (the original stimulus uses a premise about the future to support a conclusion about the future, while the correct answer uses a premise about the past to support a conclusion about the past).

Not quite parallel!
(A) This argument is flawed, but not in the same way as the stimulus. The author relies on a premise about the past to make a prediction about the future. It's also not clear that the "price of gasoline" is an average price - if that's the ONLY price of gasoline, without variation, then all gasoline would behave the same way. Additionally, while one might think of "my gasoline" as a subset of "all the gasoline", it's not as clear a part/whole distinction as that of groceries/butter&eggs or under-20s/4th-graders.

(B) This argument is flawed, but not in the same way as the stimulus. The premise gives us two options, then decrees one option "unlikely". From that, the author concludes the other option "will" occur. This switch from a mere probability to a certainty is a flaw, but we're looking for a part/whole and average issue.

(D) This argument might appear to deal in part/whole issues, but it doesn't! While sugar is a "part" of ice cream, the premises lay out a specific conditional relationship between them: When the sugar price increases, the ice cream price increases. A second premise trips that conditional: the sugar price is expected to increase next month. Following the conditional, we conclude: the ice cream price can be expected to increase next month. This argument structure is about the use of a conditional, not part/whole or average issues. And it's a valid argument!

(E) Similar to (D), this argument is a valid argument based on a conditional premise. The second premise trips the conditional: the 20-30 group will decline. Following the conditional, we can conclude that the real estate prices will decline over the same time period.

[hwangbo.edu]

Discovered error on p68 of the 4th Edition Practice Book I: 10 Real LSATs Grouped by Type.

1. For PT40, G2 (top center of page), one of the diagrammed frames fails to capture a rule (if both in: H-G):

i. F L (I, H, M/G) | K G/M

2. Recommend replacing with two frames (for a total of three):

F L (I, H, M) | K G

and

F L (I, H-G) | K M

[ManhattanPrepLSAT1]

Discovered error on p68 of the 4th Edition Practice Book I: 10 Real LSATs Grouped by Type.

1. For PT40, G2 (top center of page), one of the diagrammed frames fails to capture a rule (if both in: H-G):

i. F L (I, H, M/G) | K G/M

2. Recommend replacing with two frames (for a total of three):

F L (I, H, M) | K G

and

F L (I, H-G) | K M

Hey hwango! Thanks for your recommendation. For the record, the curriculum team loves this sort of discussion, and I'll pass it their way.

I'm sure you'll find other solutions with possible edits that make processing the information easier for you than what we came up with. And we highly recommend that you do. Just keep in mind that we all process organized information in our own (often) unique ways. Framing for example, is a topic on which not all LSAT gurus have the same opinion. Some LOVE framing and use it all the time. Others prefer a more plug-and-chug method confident that they're fast enough to test out the hypotheticals they need to answer the questions. Even those who use frames may not agree on how best to use them. More frames, enabling greater precision, but requiring your eyes to skim through more material. Or fewer frames, less material to get lost in, but also less information fully determined within those frames.

As part of your LSAT journey, I challenge you to experiment with your approach and find the path that works best for you!

[hwangbo.edu]

Hey hwango! Thanks for your recommendation. For the record, the curriculum team loves this sort of discussion, and I'll pass it their way.

As part of your LSAT journey, I challenge you to experiment with your approach and find the path that works best for you!

Thanks for your response and good advice. I agree framing (and to what degree) is a judgment call specific to tester and game. Certainly, any game can be solved without framing, yet some games do lend a clear advantage to framing, while for other games framing wastes time or adds confusion. As per your advice, I do find practicing every game both with and without frames useful - to practice framing and cultivate a quick sense of when to do so.

Just anecdotal: I used to almost never frame and just plow into the game but, over time working more logic games, I found it mentally useful to consider how to frame any given game - whether or not it's applied - helps to push together rules and distributions (stuff you do anyway = no additional time) to glean inferences and an overall "feel" for the game. Cheers!