PrepTest 55: Oct 2008..can anyone help me with the LR 24,25 Forum

[deathviaboredom]

Some twentieth-century art is great art. All great art involves original ideas, and any art that is not influential cannot be great art.
Each of the following statements follows logically from the set of statements above EXCEPT:
A) some influential art involves great ideas
B) some twentieth-century art involves original ideas.
C) only art that involves original ideas is influential
D) only art that is influential and involves original ideas is great art.
E) Some 20th century art is influential and involves original ideas.

AND

Advertisement: Researchers studied a group of people trying to lose wieght and discovered that those in the group who lost the most weight got more calories from protein than from carbohydrates and ate their biggest meal early in the day. So anyone who follows our diet, which provides more calories from protein than from anything else and which requires that breakfast be the biggest meal of the day, is sure to lose weight.

The reasoning of the advertisement is most vulnerable to the criticism on the grounds that the advertisement overlooks the possibility that

a) eating foods that derive a majority of their calories from carbohydrates tends to make one feel fuller than does eating foods that derive a majority of their calories from protein
b) a few of the people in the group studied who lost significant amounts of weight got nearly all of their calories from carbohydrates and ate their biggest meal at night.
c) the people in the group studied who increased their activity levels lost more weight on average than those who did not, regardless of whether they got more calories from protein or from carbohydrates
d) some people in the group studied lost no weight yet got more calories from protein than from carbohydrates and are their biggest meal early in the day
e) people who eat their biggest meal at night tend to snack more during the day and so tend to take in more total calories than do people who eat their biggest meal earlier in the day

[Cambridge LSAT]

Here's a breakdown for number 25.

20A: twentieth-century art
GA: great art
IA: influential art
OI: original ideas

The stimulus provides the following three statements:
20A <--some--> GA
GA → OI
~IA → ~GA

Taking the contrapositive of the third statement (GA → IA), we can chain everything together like so:
20A <--some--> GA → OI and IA

(A) IA <--some--> OI
Since GA leads to both OI and IA, there must be some overlap between these two.

(B) 20A <--some--> OI
We can follow the arrows to infer that some 20A involves OI.

(C) IA → OI
Correct. We cannot infer a conditional relationship between these two.

(D) GA → IA and OI
This is inferable, since GA leads to both OI and IA.

(E) 20A <--some--> IA and OI
This is basically an extension of (B) in that it includes both, as opposed to just one, of the stated necessary conditions for GA.

[bhan87]

For 25. The stimulus assumes that the diet (big breakfast and protein) is what caused the weight loss when it only has a correlation. However, it could be that the type of people who follow that diet have different HABITS that cause them to both follow the diet above and lose weight.

Answer E demonstrates this point. It doesn't have to be the case that the diet caused the weight loss, but rather the people who tend to follow the diet snack a whole lot less, which explains the correlation

[deathviaboredom]

For 25. The stimulus assumes that the diet (big breakfast and protein) is what caused the weight loss when it only has a correlation. However, it could be that the type of people who follow that diet have different HABITS that cause them to both follow the diet above and lose weight.

Answer E demonstrates this point. It doesn't have to be the case that the diet caused the weight loss, but rather the people who tend to follow the diet snack a whole lot less, which explains the correlation

E is the wrong answer.

[bhan87]

For 25. The stimulus assumes that the diet (big breakfast and protein) is what caused the weight loss when it only has a correlation. However, it could be that the type of people who follow that diet have different HABITS that cause them to both follow the diet above and lose weight.

Answer E demonstrates this point. It doesn't have to be the case that the diet caused the weight loss, but rather the people who tend to follow the diet snack a whole lot less, which explains the correlation

E is the wrong answer.

*facepalm*

[Jeffort]

For 25. The stimulus assumes that the diet (big breakfast and protein) is what caused the weight loss when it only has a correlation. However, it could be that the type of people who follow that diet have different HABITS that cause them to both follow the diet above and lose weight.

Answer E demonstrates this point. It doesn't have to be the case that the diet caused the weight loss, but rather the people who tend to follow the diet snack a whole lot less, which explains the correlation

E is the wrong answer.

Plus that is question #24 not 25, and the credited answer choice isn't (E) for either #24 or 25 so we cannot blame a typo for that mistake.

[mac35352]

if anything E explains why the diet recommends eating earlier. I think if anything it strengths the argument.

[zreinhar]

Answer to second question is D

It shows that some people didn't lose weight which directly contradicts the stimulus that a person participating in the diet is "sure" to lose weight.