In 1980 a researcher examined different indicators of hair health in a

Question

Source: 800 score

In 1980 a researcher examined different indicators of hair health in a group of 14-year-olds living in Bali, and found their hair to be in healthy condition. In 2000 she examined the same group again, and found that those who had worn the local white hats for the past 20 years still had healthy hair, whereas those who had worn the local black hats suffered from slight hair loss. Those who hadn’t worn a hat at all had lost all of their hair. The researcher deduced that (a) hats keep the sun from damaging hair, and (b) a white-colored cover provides better protection from the sun than a black one does.

Select a statement that supports both of the researchers’ conclusions, (a) and (b). Then select a statement that weakens both conclusions. Make only two selections, one in each column.

zhanbo · Accepted Answer

The statement should either "support  both " or "weaken  both ".

(a) hats keep the sun from damaging hair
(b) a white-colored cover provides better protection from the sun than a black one does.

Let's review each of the statement:
(1) The black Balinese hats are made of polyester, known to increase hair loss.
It only touches black hat. It does not touch (a) at all. Eliminated.

(2) In Bali, white hats are only worn in closed places with no sunlight.
At first glance, it only touches black hats. 
But it certainly weaken (a) and (b) in the sense that "protection from the sun" is nonsensical.

(3) White hats are worn too tightly in Bali, a practice that increases hair loss.
It actually contradicts with the premise. There is no hair loss with white hats. It is eliminated.

(4) Hat wearers use wax, which decreases hair loss, but less wax is needed in black hats.
This is a really interesting statement. It explains the observed phenomenon. It also touches both white and black hats.
But does it  support  or  weaken  both?
It is the wax, not hats, that provides protection for hair. From this perspective, it weakens both (a) and (b).
But a casual observer can also claim it supports both.

(5) Balinese who ceased wearing hats lost more hair than those who kept wearing black hats.
It does not touch (b)

(6) Traditionally, Balinese always wear the same color hat as their ancestors did.
It does not really matter with regards to (a) or (b).

Eventually, my answer is:
 Weaken both  -> In Bali, white hats are only worn in closed places with no sunlight.
 Supports both  ->Hat wearers use wax, which decreases hair loss, but less wax is needed in black hats.

false9 · Answer

Supports both - Balinese who ceased wearing hats lost more hair than those who kept wearing black hats.

Weakens Both - White hats are worn too tightly in Bali, a practice that increases hair loss.

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soudipsengupta · Answer

There are two parts of the conclusion:
a) The researcher deduced that hats keep the sun from damaging hair
b) The researcher deduced that a white-colored cover provides better protection from the sun than a black one does.

The question asks to select one option that strengthens both arguments and one option that weakens both arguments.

1.   Strengthen:

"Balinese who ceased wearing hats lost more hair than those who kept wearing black hats."

The above strengthens both arguments because of the following reasons:
a) The researcher concluded a cause and effect relationship between wearing hats and having more protection against the sun. By ceasing to wear hats, we take away the cause, and since in this way hair loss increased even more than those who wear black hats, the argument is surely strengthened.
b) In this case we will have to assume that at least some Balinese who ceased wearing hats altogether used to wear white hats. Then the fact that ceasing to wear hats (some white) and the evidence provided in the argument that those who wore white hats suffered no hair loss vs some hair loss experienced by those who wear black hats, we can say that ceasing to wear white hats increased hair loss to extents greater than hair loss experienced by those who wear black hats strengthens the argument that claims white hats protect hair from sun more than black hats do.

2.   Weaken

"Hat wearers use wax, which decreases hair loss, but less wax is needed in black hats."

Not too positive about the word "needed" here, but this choice gives an alternate reason for lack of hair loss, and by showing that those who wore black hats may have used less wax this choice implies that wax instead of wearing hats prevent Balinese from losing hair, and the color of hats might not have anything to do with hair loss or lack thereof.

sshwetima · Answer

In 1980 a researcher examined different indicators of hair health in a group of 14-year-olds living in Bali, and found their hair to be in healthy condition. In 2000 she examined the same group again, and found that those who had worn the local white hats for the past 20 years still had healthy hair, whereas those who had worn the local black hats suffered from slight hair loss. Those who hadn’t worn a hat at all had lost all of their hair. The researcher deduced that (a) hats keep the sun from damaging hair, and (b) a white-colored cover provides better protection from the sun than a black one does.

Select a statement that supports both of the researchers’ conclusions, (a) and (b). Then select a statement that weakens both conclusions. Make only two selections, one in each column.

Supports both    Weakens both    Statements   
       The black Balinese hats are made of polyester, known to increase hair loss.   - not providing any idea regarding white hats  
    Weakens both  In Bali, white hats are only worn in closed places with no sunlight. -  If all the conclusions are made based on the fact that no sunlight was present in the area, all conclusions will be shattered    
       White hats are worn too tightly in Bali, a practice that increases hair loss.   
       Hat wearers use wax, which decreases hair loss, but less wax is needed in black hats.  - use of wax neither supports nor weakens the conclusion  
  Supports    Balinese who ceased wearing hats lost more hair than those who kept wearing black hats. -  it provides a support by providing negative impact of not wearing hat    
       Traditionally, Balinese always wear the same color hat as their ancestors did. , irrelevant

zhanbo · Answer

Nobody got it right mainly because it is virtually impossible to determine that statement that "White hats are worn too tightly in Bali, a practice that   increases   hair loss" can support both (a) and (b).

How can it provide support to “a white-colored cover provides better protection from the sun than a black one does"? It also contradicts with the premise that people who wore white hat did not suffer from hair loss.

Will you please provide some explanations? Thanks!

Sajjad1994 · Answer

Explanation

I have solved this question just now and I am sure there might be some problem with the OA given with the source (This question belongs to Exampal GMAT Prep).

The logical answer should be:

Strengthen Both:  Hat wearers use wax, which decreases hair loss, but less wax is needed in black hats.
 Weaken Both:  In Bali, white hats are only worn in closed places with no sunlight.

Here is the detailed explanation:

The black Balinese hats are made of polyester, known to increase hair loss.

This option strengthens only option  (b)  above but does nothing to  (a)

In Bali, white hats are only worn in closed places with no sunlight.

This option weakens both  (a)  and  (b) . It tells us that white hats have no superiority over black hats and that hats did not keep the sun from damaging hair.

White hats are worn too tightly in Bali, a practice that increases hair loss.

This is the polar opposite to what is stated in the premise and conclusion above it simply says that all written above is wrong. It has no logical connection though.

Hat wearers use wax, which decreases hair loss, but less wax is needed in black hats.

This statement strengthens the above argument and both parts of the conclusion. It tells us why white hats are superior to black hats and that wearing hats does matter.

Balinese who ceased wearing hats lost more hair than those who kept wearing black hats.

It strengthen  (a)  above but did not tell anything about  (b)

Traditionally, Balinese always wear the same color hat as their ancestors did.

This statement is totally unrelated.

Does this all make sense?

kratos0906 · Answer

I have a few problems with this explanation.

In Bali, white hats are only worn in closed places with no sunlight.

This statement does not mention black hats. So while we can certainly conclude that hats did not keep the sun from damaging hair since hats are not even worn outside, how can this statement weaken the argument that white hats are better than black hats for protection against the sun. Is it the fact that since hats are not keeping the sun from damaging hair, the colour of the hat does not matter? Any colour hat will be unable to protect the hair, so it is pointless to compare two different colours of hat?

Hat wearers use wax, which decreases hair loss, but less wax is needed in black hats.

While your interpretation of this statement does make sense, my interpretation is slightly different. It can be concluded from this statement that it's actually the wax and not the hat itself that is protecting the hair. So if a person only applies wax to their hair it should protect their hair from the sun. So we can technically weaken both the statements from this. First, its not the hats that are keeping the sun from damaging the hair, its actually wax. Second, we can't compare two different colours of hats, since its technically the wax that's protecting the hair.

srik410 · Answer

I struggled with this a bit. The answer to the strengthens both question stands corrected. The logic class I took a while back comes to the rescue.

A implies B: Hats provide protection from the sun
A implies C implies B: Hats wearers happen to use wax, which in turn protects from the sun

The second statement can be simplified to the first statement. ie A-> C and C->B can be merged to A -> B. Hope this clarifies

In 1980 a researcher examined different indicators of hair health in a

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Supports both	Weakens both	Statements
		The black Balinese hats are made of polyester, known to increase hair loss.
		In Bali, white hats are only worn in closed places with no sunlight.
		White hats are worn too tightly in Bali, a practice that increases hair loss.
		Hat wearers use wax, which decreases hair loss, but less wax is needed in black hats.
		Balinese who ceased wearing hats lost more hair than those who kept wearing black hats.
		Traditionally, Balinese always wear the same color hat as their ancestors did.

GMAT Two-part Analysis (TPA) Questions

In 1980 a researcher examined different indicators of hair health in a

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