#22 - A scientist made three observations: (1) in the

[Administrator]

Complete Question Explanation

Evaluate the Argument. The correct answer choice is (E)

The stimulus describes a scientist's observations. First, in temperate zones, food is more plentiful in the ocean than in fresh water. Second, temperate zone migratory fish spawn in fresh water and mature in the ocean. Third, migratory fish need more food as they mature. On the basis of these observations, the scientist hypothesizes that migratory fish migrate (from fresh water to ocean, or vice versa) to get more food as they mature. Then the scientist observes that in the tropics, migratory fish spawn in the ocean and mature in fresh water (reverse of temperate migratory fish). This would seem to discredit his hypothesis, right?

Clearly, unless in the tropics, food is more plentiful in fresh water than in the ocean, which would explain why tropical fish migrate from ocean to fresh water as they mature. So in order to tell if the hypothesis holds, we need to know the distribution of food in the tropics (our pre-phrase). Namely, in the tropics, is the distribution of food reversed?

This is an evaluate question; in this case, we are evaluating the scientist's hypothesis, namely, whether it holds. The answer choices present a list of questions: answering that question one way would discredit the hypothesis; answering the opposite way would do the opposite. Answering yes to our pre-phrase would validate the hypothesis and explain the subsequent reverse behavior of tropical fish vis a vis temperate fish. Answering no would discredit it.

Answer choice (A): This answer choice is incorrect. Temperatures are irrelevant to the scientist's hypothesis, and no matter what the temperatures are in the temperate zones, the hypothesis is unaffected. As such, it would neither validate nor discredit the hypothesis. The key to the hypothesis is the distribution of food.

Answer choice (B): This answer choice is incorrect. Yes, it talks about food, but this is a red herring (no pun intended). The problem here is that it does not mention the distribution of food between ocean and fresh water.

Answer choice (C): This answer choice is incorrect because it does not mention food or the distribution thereof.

Answer choice (D): This answer choice is incorrect. Like (C), the information about the distribution of species is irrelevant to the hypothesis.

Answer choice (E): This is the correct answer choice because it matches our pre-phrase, explained above why it is right.

[voodoochild]

Experts,
Here's my analysis for B,C and D (I chose E, but I want to make sure that I am on the right track)

B- Using Variance test, similar or dissimilar types of food could be a strengthener for the causality between food and migratory behavior because in the end, it's the food that's affecting the migratory behavior. Eliminate.
C-same/different type of species? Yes - this could explain a different causal link between migratory behavior and species - Both options will WEaken the conclusion.
D-The number of species is irrelevant. 1 species vs. 100 (maximum) species doesn't have any effect. Irrelevant.

I am mainly concerned about "double strengtheners" and "double weakeners" in choice B and C. Please let me know whether my understanding is correct.


Thanks

[BethRibet]

Hi Voodoochild,

For B, the important thing to notice is that there is no information in the passage indicating how or whether the type of food eaten bears on the hypothesis. One could only evaluate the hypothesis based on differences in type of food in tropic or temperate zones, by assuming facts or information not in evidence (for instance, whether some types of food are more nourishing). Therefore, while it might conceivably be relevant to know, this is not the "most helpful" answer.

For C, again, we have no information from the passage indicating how the species of fish bears on the hypothesis. So the result is the same -- you could only use this information to evaluate the hypothesis, if you had more information that is not provided. Therefore, this is not the "most helpful" answer, even if it may have some relevance.

D, as you note, is also irrelevant, for similar reasons.

E is correct because it speaks directly to the premise most relevant to the hypothesis, that is the comparative availability of food in ocean rather than fresh water.

take care,
Beth

[Snomen]

I got this one correct, but my issue is time. It took me some time to understand the stimulus and answer the question. Are there any tips or recommendations on time for these long stimulus passages?

[Adam Tyson]

Patience, snomen! Some stimuli will just take longer, and they are written to slow you down. It's no surprise to find something this late in the section that is a drag on our time, and sometimes that might mean we should skip it and move along if time is very short.

The other things you can and should do to speed things along are 1) prephrase - come up with at least a general idea of what the answer needs to talk about before looking at the answers - and 2) sort them into losers and contenders without stopping to give them a lot of thought or analysis. Save that analysis until after the sorting is done. There's a big reward waiting for you if you do that right in this case, because the prephrase should be something along the lines of "what's up with the food in the tropics? Is it like the temperate zones, or opposite?" and only one answer even attempts to address the issue of food availability, answer E. You could go through the first four answers quickly and either dismiss them (because they don't touch on your prephrase) or keep them because you just don't know if they might be important or not, and then when you get to E you should go "awesome, that was just what I was looking for!" and select it no matter how many other answers you had set aside for further consideration, if any.

It might take a while to read the stimulus, but with the right approach to LR questions (prephrasing and sorting) you should then get through the answers very quickly and be able to very confidently select the right answer. You should be happy to take that speed/accuracy trade-off every time!