Native Hawaiian temples on the island of Maui may have been built much

Question

Native Hawaiian temples on the island of Maui may have been built much more quickly than within the 250-year span previously supposed by scientists, significantly altering scientists’ estimates of the pace of sociopolitical change within Pacific Island cultures. Native Hawaiian oral histories hold that sometime around 1600, a ruler named Pi’ilani united two opposing chiefdoms on Maui into a peaceful religious state. But archaeologists had been unable to scientifically confirm the event, in part because of limitations with radiocarbon dating.

Recently, however, knowing that coral takes in uranium-238 from seawater, researchers used a different radiometric technique to date bits of branch coral collected from living reefs and incorporated ornamentally into the walls of several temples during construction. The technique measures both uranium-238 and thorium-230, into which the uranium decays at a known rate. Dates on the samples that best reflect when they were harvested—those from the coral branch tips —ranged from 1608 to 1638, suggesting there was intensive temple building during that time. Because, the researchers contend, temples served as centers for control of production and the collection of surplus goods, it is likely that the construction boom accompanied a profound shift in sociopolitical structure. The events described by local oral histories agree with these new dates, and the temples provide tangible archaeological evidence that this sociopolitical shift happened in the span of a single generation of Hawaiians.

1. It is most reasonable to infer that the author uses the phrase "single generation of Hawaiians" in the final sentence of the passage to imply that

A. coral was used decoratively in Hawaiian temples only for a relatively short period
B. the temples likely served only a portion of the population on Maui
C. the researchers’ use of the thorium-230 dating method is commendable
D. the researchers’ study is consistent with oral histories regarding Pi’ilani
E. the pace of sociopolitical change within Pacific Island cultures was more uneven than most researchers have supposed

2. Which of the following most accurately expresses the main point of the passage?

A. New evidence found by researchers demonstrates that the sociopolitical reforms in a particular region were short lived.
B. Recent scientific research supports oral histories and has improved scientists’ understanding of human history in a particular region.
C. Oral histories in a particular region have prompted researchers to question previous research into the sociopolitical history of the region.
D. Researchers searching for new evidence regarding the history of social change in a particular region have turned to oral histories from the region.
E. Researchers are using an innovative dating technique to study the social history of a particular region.

3. Which of the following can most reasonably be inferred from the passage?

A. The coral in the temple walls did not take in thorium-230 after being harvested from the sea.
B. Coral was used in the building of the temples partly to make the temples more structurally sound.
C. The coral incorporated into the temple walls is made up primarily of branch tips.
D. Researchers have identified which reefs supplied the coral incorporated into the temples.
E. Only the tips of the branch coral take in uranium-238 from seawater.

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Show Answer Question #1

Official Answer

D

Show Answer Question #2

Official Answer

B

Show Answer Question #3

Official Answer

A

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GMATNinja · Accepted Answer

Question 3

We're told that the coral takes in uranium-238 from seawater and that the uranium  decays into  thorium-230. There's nothing in the passage suggesting that coral takes in thorium-230 directly, either before or after harvesting.

Is it possible that the coral in the temple walls DID take in thorium-230 after being harvested from the sea? Sure. There's nothing in the passage to  prove  that it didn't. But if that were in fact the case, why would the researchers use a radiometric dating technique that relies on thorium-230 measurements?

And again, we're told that the thorium-230 comes from the uranium, so (A) is reasonable to infer and should be kept.

More importantly, we can eliminate the other options. Here, have another:

We're told that bits of branch coral were incorporated ornamentally into the temple walls, but the passage doesn't say anything about using the coral for a  structural  purpose. (B) is out.

The branch tips were used by the researcher because those are the samples whose dates "best reflect when they were harvested".

But that doesn't tell us anything about the relative proportion of coral branch tips to other coral parts used in the temple walls. For all we know, branch tips represented only a small proportion of the coral used. Regardless, the researchers used the branch tips because -- for whatever reason -- the harvest dating of the branch tips is more reliable. (C) is out.

The passage doesn't say anything about identifying the  specific  living reefs that supplied the coral found in the temple walls, so (D) is out.

Again, the branch tips were used by researchers because they yield the most accurate harvest dates. That doesn't mean that the other parts of the coral do NOT take in uranium-238. Maybe they do, maybe they don't. But the passage doesn't tell us either way, so (E) is out.

(A) is the best option.

GMATNinja · Answer

Question 1

Question 1 asks why the author included a particular detail of the passage. To understand this kind of thing, it's important to look at the bigger picture. Why did the author write each paragraph, and the passage as a whole? Answering this will allow you to see the purpose of a smaller detail.

So, why did the author write each paragraph?

In the first paragraph, the author  suggests that a longish timeline of temple-building may be wrong, but says that scientists haven't been able to confirm  one way or the other. Perhaps the 250-year span of temple building is incorrect, and the actual timeline matches up with oral reports of a big change sometime around 1600. We just don't know.

In the second paragraph, the  author provides evidence to confirm the shorter timeline, which matches up with oral reports from the native population.

With this bigger picture in mind, why did the author use the phrase "single generation of Hawaiians" in the final line? Well, a single generation is a short period of time. So, this language is there to show that the new studies and the oral histories match up well -- both indicate that the changes occurred within a short period of time.

That aligns nicely with (D): "the researchers’ study is consistent with oral histories regarding Pi’ilani."

(D) is the correct answer to question 1.

I hope that helps!

Sajjad1994 · Answer

Explanation

3. Which of the following can most reasonably be inferred from the passage?

Explanation

A.   This statement can be reasonably inferred from the passage. The passage mentions that researchers used a radiometric technique to date bits of branch coral collected from living reefs and incorporated ornamentally into the walls of several temples during construction. The technique measures both uranium-238 and thorium-230, into which the uranium decays at a known rate. The passage does not mention any process that would cause the coral to continue taking in thorium-230 after being harvested. Therefore, it is reasonable to infer that once the coral was harvested from the sea and incorporated into the temple walls, it ceased to take in thorium-230.

B.  The passage mentions the use of coral branches ornamentally in the construction of temples and how these samples were used for dating purposes. However, there's no indication that the primary purpose of using coral was for structural reinforcement.

C.  While the passage mentions that researchers dated bits of branch coral collected from living reefs and incorporated ornamentally into the walls of several temples, it does not specify whether the coral used in the temples was primarily made up of branch tips.

D.  While the passage discusses the use of coral from living reefs in temple construction, it does not mention whether researchers identified specific reefs that supplied the coral.

E.  While the passage indicates that researchers dated samples from the coral branch tips, it does not explicitly state that only the tips of the branch coral take in uranium-238 from seawater. It simply mentions that the branch coral was used for dating purposes.

Answer: A

sachi-in · Answer

Summary:  The (dating) technique measures both uranium-238 and thorium-230, into which the uranium decays at a known rate. Dates on the samples that best reflect when they were harvested—those from the coral branch tips —ranged from 1608 to 1638, suggesting there was intensive temple building during that time

3. Which of the following can most reasonably be inferred from the passage?

A. The coral in the temple walls did not take in thorium-230 after being harvested from the sea. -   If Th-230 was taken in then it would cause errors in measurement of age ( more Th-230 acummulation mean more decay and even older time frame. We measure the age by Thorium decay, if additional Th-230 is present it would introduce errors )  
B. Coral was used in the building of the temples partly to make the temples more structurally sound. -  We don't know that 
C. The coral incorporated into the temple walls is made up primarily of branch tips. -    We don't know what is the overall composition, we just know tips were used for research  
D. Researchers have identified which reefs supplied the coral incorporated into the temples. -   Researchers may have identified the reefs or maynot they just needed to take the samples from the coral brach tips used in temple construction, they don't need to extract it from the ocean  
E. Only the tips of the branch coral take in uranium-238 from seawater. -  We don't know that, scientists only use the tips for the experiment

Of A, C, D  only A is Correct

Sajjad1994 · Answer

Explanation

2. Which of the following most accurately expresses the main point of the passage?

Explanation

The passage primarily discusses recent scientific research that supports the oral histories of Native Hawaiians regarding sociopolitical changes on the island of Maui. The researchers utilized an innovative radiometric dating technique involving coral to obtain dates that align with the oral histories, indicating intensive temple building during the early 17th century. This discovery significantly alters scientists’ previous estimates of the pace of sociopolitical change in Pacific Island cultures and improves their understanding of human history in the region.  (B)  is correct.

A.  While the passage does reveal new evidence regarding the timing of sociopolitical changes on Maui, it does not specifically indicate whether these reforms were short-lived or not. The focus is more on aligning the scientific findings with oral histories and improving understanding of historical timelines, rather than assessing the duration of the reforms.

C.  The passage does not suggest that oral histories prompted researchers to question previous research. Instead, it highlights how recent scientific research, using an innovative dating technique, corroborates the oral histories, thus supporting them and advancing understanding.

D.  While the passage discusses the use of oral histories alongside scientific research, it does not imply that researchers specifically turned to oral histories as their primary source of evidence. The oral histories were used in conjunction with the innovative dating technique to enhance understanding.

E.  While the passage does discuss the use of an innovative dating technique, the main point is not simply about the technique itself but rather about how this technique has contributed to improving scientists’ understanding of human history in the region, particularly in relation to sociopolitical changes.

Answer: B

Sajjad1994 · Answer

Explanation

1. It is most reasonable to infer that the author uses the phrase "single generation of Hawaiians" in the final sentence of the passage to imply that

Explanation

A.  While the dating of coral samples suggests a relatively short period of intensive temple construction, it does not necessarily imply that coral was only used decoratively for a short period. The focus is on the construction period, not specifically on the duration of coral usage.

B.  The passage primarily discusses the construction of temples and the sociopolitical changes associated with them, but it does not provide evidence to suggest that temples served only a portion of the population.

C.  While the passage mentions the use of a different radiometric dating technique involving uranium-238 and thorium-230, it does not provide an evaluation of the method's commendability. The focus is on how this method helped researchers obtain more precise dates for the temple construction, rather than evaluating the method itself.

D.   is correct because the passage explicitly states that the events described in local oral histories align with the new dates obtained from the coral samples. The researchers' study provides tangible archaeological evidence supporting the oral histories regarding Pi'ilani's role in the sociopolitical changes on Maui.

E.  While this statement might seem plausible given the context of the passage, it is not explicitly supported by the passage itself. The passage primarily focuses on the specific case of sociopolitical change on Maui related to temple construction and does not make a broader statement about the pace of change within all Pacific Island cultures.

Answer: D

KarishmaB · Answer

Question 3. 3. Which of the following can most reasonably be inferred from the passage? A. The coral in the temple walls did not take in thorium-230 after being harvested from the sea. B. Coral was used in the building of the temples partly to make the temples more structurally sound. C. The coral incorporated into the temple walls is made up primarily of branch tips. D. Researchers have identified which reefs supplied the coral incorporated into the temples. E. Only the tips of the branch coral take in uranium-238 from seawater. Between A and E This is what a branch coral looks like: https://en.wikipedia.org/wiki/Branch_coral Bits of branch coral were harvested from the reefs and used to decorate the temples. The dating technique measures both uranium-238 and thorium-230, into which the uranium decays at a known rate. It helps here if you vaguely understand how carbon dating works. A living plant absorbs has both carbon14 and carbon 12. The two are in a certain proportion at that time (for ease say 5% is carbon 14 and rest 95% is carbon 12). Once the plant dies, it stops absorbing both carbons and carbon 14 starts decaying at a fixed pace into nitrogen. Carbon 12 stays as it is. So looking at the propotion of carbon 14 vs carbon 12 in the plant after many years, one can figure out its age. Say if there is 95 gms of carbon 12 and 5 gms of carbon 14 then the plant just died. If there is 95 gms of carbon 12 and 2.5 gms of carbon 14, it means the plant died about 5000 years ago (half life of carbon 14) etc. Here the coral absorbs uranium-238 from seawater so once it is harvested, it stops absorbing it. It starts decaying into thorium at a fixed pace. We can use radioactive dating technique only if it doesn't absorb anymore thorium too. This is what option (A) says. A. The coral in the temple walls did not take in thorium-230 after being harvested from the sea. It can be reasonably inferred. E. Only the tips of the branch coral take in uranium-238 from seawater. The only thing we are given about the tips is this: The samples that best reflect when they were harvested were those from the coral branch tips. They were used to figure out the date when the coral branches were harvested and these dates ranged from 1608 to 1638 Does it mean that only the tips take in uranium 238? No. All we are told is that they are the most reliable indicators - for whatever reason. Other parts could be taking in uranium 238 too. Answer (A) GMAT-Club-Forum-63cyklqh.png GMAT-Club-Forum-y7jt5rwi.png GMAT-Club-Forum-l8yr6tsl.png GMAT-Club-Forum-ogcdtmdj.png

Blackcrow1972 · Answer

Q3) Option C
This inference is based on the principles of the uranium-thorium dating method described in the passage. The method relies on measuring the decay of uranium-238 into thorium-230, which occurs at a known rate. For the dating to be accurate, it must be assumed that no thorium-230 was added to the coral after it was removed from the sea (e.g., after incorporation into the temple walls). If thorium-230 had been taken in after the coral was harvested, it would disrupt the reliability of the dating method, and the researchers would not have obtained accurate results.

sachingarGmat · Answer

FOR QUESTION 3:

Look at this line:

"researchers used uranium–thorium dating... and used dates from coral branch tips that best reflect when they were harvested"

For this to work:

The coral must stop changing (stop taking in or forming thorium-230) after it is removed from the sea
Otherwise, the measured date would not reflect the harvest time

So we can infer:
✔ After harvesting, coral does not continue the same process affecting the measurement

That supports A.

gullyboy09 · Answer

Hi  IanStewart ,  MartyMurray , can you please help me with the below question? This came in my mock today, it took me some time to get it in the exam as to me A was more like an assumption that researchers needs to make, and not an inference.

3. Which of the following can most reasonably be inferred from the passage?

A. The coral in the temple walls did not take in thorium-230 after being harvested from the sea.
B. Coral was used in the building of the temples partly to make the temples more structurally sound.
C. The coral incorporated into the temple walls is made up primarily of branch tips.
D. Researchers have identified which reefs supplied the coral incorporated into the temples.
E. Only the tips of the branch coral take in uranium-238 from seawater.

IanStewart · Answer

Yes, I agree answer A does sound more like an assumption than an inference, and it would be an assumption if we were asked what the scientists are assuming when they stand by the accuracy of the radiometric dating. I think most answers above are justifying A as an assumption, not as an inference, even if they say otherwise. That said, I also think it's either a very subtle question, or a question that doesn't really have a good answer. I can only interpret answer A as an inference in this way: overall, the passage says, simplifying, "science used to disagree with historical accounts (scientists assigned a 250-year range to temple construction, while oral histories support a sudden development around 1600). Using new techniques, science now agrees with historical accounts." So if you take as a sort of premise that the historical accounts are correct, and here I'm reading a lot into the use of the word "confirm" in the first paragraph, we can infer that the radiometric dating produced a correct date, and thus that the samples were not contaminated.

That does feel tenuous to me, but it can't be true that a test taker needs to understand radiometric dating to answer a GMAT question, and other explanations in this thread are certainly not what the test has in mind here. I don't find the right answer all that satisfying, but it is the only answer that has even a remote justification -- the remaining answers are very clearly not inferences, since we have no information in the passage that would let us say anything about the statements in B, C, D and E.

guddo · Answer

3. Which of the following can most reasonably be inferred from the passage?

The passage says researchers dated coral by measuring uranium-238 and thorium-230, because uranium-238 decays into thorium-230 at a known rate. For this dating to reflect when the coral was harvested, the thorium-230 in the coral must have come from that decay process, not from later outside absorption.  The key inference  is that the coral did not take in  new thorium-230 after harvest .

A. The coral in the temple walls did not take in thorium-230 after being harvested from the sea.

Correct. If the coral had taken in thorium-230 after being harvested, the uranium-thorium dating would not reliably indicate when the coral was harvested. The passage treats the dates as reflecting harvest time, so this is a reasonable inference.

B. Coral was used in the building of the temples partly to make the temples more structurally sound.

Wrong. The passage says the coral was incorporated ornamentally, not structurally.

C. The coral incorporated into the temple walls is made up primarily of branch tips.

Wrong. The passage says branch tips gave the best harvest dates, but it does not say most of the coral was branch tips.

D. Researchers have identified which reefs supplied the coral incorporated into the temples.

Wrong. The passage mentions living reefs generally, but does not say researchers identified the specific source reefs.

E. Only the tips of the branch coral take in uranium-238 from seawater.

Wrong. The passage says coral takes in uranium-238 from seawater, not only the tips.

Answer: (A)

Native Hawaiian temples on the island of Maui may have been built much

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Native Hawaiian temples on the island of Maui may have been built much

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