Archaeologists should make greater use of satellite images in their search for Mayan ruins in the jungles of Guatemala. Though satellite photographs have proven unhelpful because of their inability to penetrate the dense tree canopy, infrared imaging translates heat signatures into distinct colors, making previously-undiscovered ruins visible.
The conclusion above is based on which of the following assumptions?
a)Infrared imaging is helpful because the heat signature of ruin sites is different from the heat signature of the surrounding jungle.
b)Archeologists in the field have not been able to discover many ruins because the jungle is impenetrable.
c)Archaeologists use both satellite technology and local folklore to theorize the location of ruins.
d)Archaeologists require special training in order to read maps produced by infrared imaging.
e) Satellite photography has not produced images of sufficient detail to locate ruins in the jungle.
I chose (e) since , "Satellite photography has not produced images of sufficient detail to locate ruins in the jungle, infrared imaging translates heat signatures into distinct colors..
Please elaborate .
If you apply the assumption negation technique, you may mistakenly choose (E). But it's incorrect.
Let's try the GMATPill approach. First focus on topic relevancy. Then apply assumption negation where necessary.
Topic relevancy. This depends on conclusion. What is the conclusion?
It's actually not the first sentence here. "Archaeologists should make greater use of satellite images..."
No, it's not that. It's more subtle here. It's:"Infrared....makes previously-undiscovered ruins visible"
Essentially, the passage changes direction and makes a new statement in favor of Infrared. Infrared is better than satellite because it "makes previously-undiscovered ruins visible".Thus, the eliminate answer choices that don't affect "Infrared being a useful choice"
My gut instinct when reading:
"Infrared" better than "satellite" because of this heat signature advantage. But for this to be true, a "Mayan ruin" should indicate a heat signature and non-Mayan objects should not. That way if we do see a heat signal, we know it is a Mayan ruin.
But without that, let's go through the answer choices.GMATPill Steps
Step 1:Check relevancy
Step 2: Then apply assumption negation if necessary:
Is (A) relevant to "Infrared being a useful choice"? Yes. Now, apply assumption negation.
Original: Infrared imaging is helpful because the heat signature of ruin sites is different from the heat signature of the surrounding jungle.
Opposite: Infrared imaging is helpful because the heat signature of ruin sites is NOT different from the heat signature of the surrounding jungle.
Opposite.....? ok well, if the heat signature of ruin sites is the SAME as the heat signature from surrounding jungle, then when we see our infrared results, we won't be able to distinguish what is Mayan, and what is jungle. We are UNABLE to distinguish and make visible the ruins. How does this compare to the conclusion of the original argument? It's opposite.
Thus assumption negation worked.
Original -> Infrared helpful, ruins visible
Opposite -> Infrared not helpful, ruins not visible
Thus (A) is a good answer choice.What about (E)?
Is (E) relevant to "Infrared being a useful choice"? No.
No....(E) is actually talking about the "+" points of satellite photography...NOT about the "+" points about Infrared..which is what the argument's topic is. Thus...it's not a valid contender to apply assumption negation.
If you do mistakenly apply the assumption negation, you'll see that it might be a contender too. But that would be wrong, it fails GMATPill's step 1, rule of relevancy