GMATPrep Reading Comp: Tackling a Science Passage - Part 2
In the first installment of this series, we deconstructed a science-based Reading Comprehension passage from the GMATPrep free exams. I gave you the full passage plus three problems, and we discussed how to solve the first problem.
Lets talk about the second one now! Here are the passage and problem again. (Note: if you havent done part 1 yet, I recommend going back there first. Do the whole passage plus three problems as a setmimic the real test!)
Prior to 1965 geologists assumed that the two giant rock plates meeting at the San Andreas Fault generate heat through friction as they grind past each other, but in 1965 Henyey found that temperatures in drill holes near the fault were not as elevated as had been expected. Some geologists wondered whether the absence of friction-generated heat could be explained by the kinds of rock composing the fault. Geologists pre-1965 assumptions concerning heat generated in the fault were based on calculations about common varieties of rocks, such as limestone and granite; but "weaker" materials, such as clays, had already been identified in samples retrieved from the fault zone. Under normal conditions, rocks composed of clay produce far less friction than do other rock types.In 1992 Byerlee tested whether these materials would produce friction 10 to 15 kilometers below the Earth's surface. Byerlee found that when clay samples were subjected to the thousands of atmospheres of pressure they would encounter deep inside the Earth, they produced as much friction as was produced by other rock types. The harder rocks push against each other, the hotter they become; in other words, pressure itself, not only the rocks properties, affects frictional heating. Geologists therefore wondered whether the friction between the plates was being reduced by pockets of pressurized water within the fault that push the plates away from each other.
The passage is primarily concerned with
(A) evaluating a method used to test a particular scientific hypothesis
(B) discussing explanations for an unexpected scientific finding
(C) examining the assumptions underlying a particular experiment
(D) questioning the validity of a scientific finding
(E) presenting evidence to support a recent scientific hypothesis
Ready? Lets do this!
These questions are from an actual GMATPrep exam that I took myselfand the questions are in the same order in which I received them. I breathed a sigh of relief when I saw this second one.
Whenever the first question is some kind of detail question, Im always a little worried that theyre not going to give me a main idea question at all. And that annoys me, because I can usually save a little time on Primary Purpose, or main idea, questionsI want to get one! So I was pretty happy when I saw this one. :)
We dont get Primary Purpose questions for every passage though. Usually, two or three out of the four passages will have some kind of general question (either main idea or purpose of one paragraph or something similar). In my experience, I usually have at least one passage with no general questionand sometimes two passages. Just FYI so you know what to expect.
Okay, lets solve this thing. This is a main idea question, as evidenced by the language primarily concerned with in the question stem. (The question stem is how you tell what kind of question you have.)
As soon as I saw that I needed the main idea, I knew what to do next: glance over my passage Map and articulate to myself what I thought the main point was. Heres my Map:
(P1) Pre-65, G: RPs heat via friction
65, H: not so hot
Why? Type of rock? Less L and G, more C? C = less friction
(P2) 92, B test: C same friction w/pressure. > press > heat
water reduce friction?
Lets see. There was this theory (before 1965), but then H tested it and the results didnt support the theory. So then people came up with a new theory that would go along with Hs findings. But then B tested something else and that didnt support the new theory! So people came up with another new theoryand then the passage ends. In other words, we dont know whether this new theory is finally the right one.
Final step! Check the answers to see what matches with that story.
(A) evaluating a method used to test a particular scientific hypothesis
To me, the passage isnt evaluating so much as just telling us stuff that happened. If it is evaluating anything, its really evaluating the overall hypotheses (the geologists keep getting it wrong!), not the methods used to test it. The author just presents the tests and results as valid or accepted. Eliminate (A).
(B) discussing explanations for an unexpected scientific finding
There was an unexpected finding. The passage does discuss what happened after the unexpected finding. I feel like there were two unexpected findings, not just one, but this one isnt terrible. Ill leave it in for now.
(C) examining the assumptions underlying a particular experiment
The passage doesnt discuss any assumptions of the experiments. H just tested something and found that it didnt match with the accepted hypothesis. The same is true for B. Eliminate (C).
(D) questioning the validity of a scientific finding
This one is so tempting! I almost fell for it. The passage definitely seems to be questioning something, but it is not questioning the validity of the experiments. It accepts that Hs results and Bs results are valid. The question is around what the hypothesis should really be, since the data doesnt support the various hypotheses put forth. Eliminate (D).
(E) presenting evidence to support a recent scientific hypothesis
Trap! The various pieces of evidence do not support the various hypotheses. Each time, the new evidence goes against the current hypothesis and the scientists have to change the original hypothesis. Eliminate (E).
By process of elimination, answer (B) is correct.
I didnt love that choiceit was kind of wishy-washy. I thought it might not be the right answer, but it does fit the available information. My one objection, that I thought there were two unexpected findings, can be overcome: the whole story starts with the one unexpected finding. Everything else happens as a result of that first one, so that's the core of the story.
I know from experience that correct answers on main idea questions are often this way; that's why I left it in. The other four were all outright wrong for some reason, so I backed my way into the correct answer. Id say this is the case maybe 50% of the time for me on Primary Purpose questions.
In the final installment of this series, well talk about the third problem in the set.
Key Takeaways for RC
(1) Map the passage. Make sure to delineate each paragraph and represent the main message (but not all of the details) in your map.
(2) As you make your map, articulate the Simple Story to yourselfand keep it very big picture. What would you tell a friend about this passage you just read? You wouldnt get into all of the specific details; youd mostly just tell her the main ideas / simple story.
(3) Main Idea questions are looking for that simple story you told yourself. A lot of the time, the answer choices will be fairly high level (or wishy-washy). Eliminate anything that you can disprove and go with what you have left.
* GMATPrep questions courtesy of the Graduate Management Admissions Council. Usage of this question does not imply endorsement by GMAC.