Oil companies need offshore platforms primarily because the oil or nat

Question

Oil companies need offshore platforms primarily
because the oil or natural gas the companies extract
from the ocean floor has to be processed before
pumps can be used to move the substances ashore.
 (5)  But because processing crude (unprocessed oil or
gas on a platform rather than at facilities onshore
exposes workers to the risks of explosion and to an
unpredictable environment, researchers are
attempting to diminish the need for human labor
 (10)  on platforms and even to eliminate platforms
altogether by redesigning two kinds of pumps to
handle crude. These pumps could then be used to
boost the natural pressure driving the flow of
crude, which, by itself, is sufficient only to bring
 (15)  the crude to the platform, located just above the
wellhead. Currently, pumps that could boost this
natural pressure sufficiently to drive the crude
through a pipeline to the shore do not work
consistently because of the crude’s content. Crude
 (20)  may consist of oil or natural gas in multiphase
states—combinations of liquids, gases, and solids
under pressure—that do not reach the wellhead in
constant proportions. The flow of crude oil, for
example, can change quickly from 60 percent liquid
 (25)  to 70 percent gas. This surge in gas content causes
loss of “head,” or pressure inside a pump, with the
result that a pump can no longer impart enough
energy to transport the crude mixture through the
pipeline and to the shore.

(30)  Of the two pumps being redesigned, the
positive-displacement pump is promising because it
is immune to sudden shifts in the proportion of
liquid to gas in the crude mixture. But the pump’s
design, which consists of a single or twin screw
 (35)  pushing the fluid from one end of the pump to the
other, brings crude into close contact with most
parts of the pump, and thus requires that it be
made of expensive corrosion-resistant material.
The alternative is the centrifugal pump, which has a
 (40)  rotating impeller that sucks fluid in at one end and
forces fluid out at the other. Although this pump
has a proven design and has worked for years with
little maintenance in waste-disposal plants,
researchers have discovered that because the swirl
 (45)  of its impeller separates gas out from the oil that
normally accompanies it, significant reductions in
head can occur as it operates.

Research in the development of these pumps is
focused mainly on trying to reduce the cost of the
 (50)  positive-displacement pump and attempting to
make the centrifugal pump more tolerant of gas.
Other researchers are looking at ways of adapting
either kind of pump for use underwater, so that
crude could be moved directly from the sea bottom
 (55)  to processing facilities onshore, eliminating
platforms.   1 
 1. Which one of the following best expresses the main ideas of the passage?

(A) Oil companies are experimenting with technologies that may help diminish the danger to workers from offshore crude processing.
(B) Oil companies are seeking methods of installing processing facilities underwater.
(C) Researchers are developing several new pumps designed to enhance human labor efficiency in processing facilities.
(D) Researchers are seeking to develop equipment that would preempt the need for processing facilities onshore.
(E) Researchers are seeking ways to separate liquids from gases in crude in order to enable safer processing.

2 
 2. The passage supports which one of the following statements about the natural pressure driving the flow of crude?

(A) It is higher than that created by the centrifugal pump.
(B) It is constant, regardless of relative proportions of gas and liquid.
(C) It is able to carry the crude only as far as the wellhead.
(D) It is able to carry the crude to the platform.
(E) It is able to carry the crude to the shore.

3 
 3. Which one of the following best describes the relationship of the second paragraph to the passage as a whole?

(A) It offers concrete detail designed to show that the argument made in the first paragraph is flawed.
(B) It provides detail that expands upon the information presented in the first paragraph.
(C) It enhances the author’s discussion by objectively presenting in detail the pros and cons of a claim made in the first paragraph.
(D) It detracts from the author’s discussion by presenting various problems that qualify the goals presented.
(E) It modifies an observation made in the first paragraph by detailing viewpoints against it.

4 
 4. Which one of the following phrases, if substituted for the word “head” in line 47, would LEAST change the meaning of the sentence?

(A) the flow of the crude inside the pump
(B) the volume of oil inside the pump
(C) the volume of gas inside the pump
(D) the speed of the impeller moving the crude
(E) the pressure inside of the pump

5 
 5. With which one of the following statements regarding offshore platforms would the author most likely agree?

(A) If a reduction of human labor on offshore platforms is achieved, there is no real need to eliminate platforms altogether.
(B) Reducing human labor on offshore platforms is desirable because researchers’ knowledge about the transportation of crude is danerously incomplete.
(C) The dangers involved in working on offshore platforms make their elimination a desirable goal.
(D) The positive-displacement pump is the better alternative for researchers, because it would allow them to eliminate platforms altogether.
(E) Though researchers have succeeded in reducing human labor on offshore platforms, they think that it would be inadvisable to eliminate platforms altogether, because these platforms have other uses.

6 
 6. Which one of the following can be inferred from the passage about pumps that are currently available to boost the natural pressure of crude?

(A) The efficiency of these pumps depends on there being no gas in the flow of crude.
(B) These pumps are more efficient when the crude is less subject to sudden increases in the proportion of gas to liquid.
(C) A sudden change from solid to liquid in the flow of crude increases the efficiency of these pumps.
(D) The proportion of liquid to gas in the flow of crude does not affect the efficiency of these pumps.
(E) A sudden change from liquid to gas in the flow of crude increases the risk of explosion due to rising pressure inside these pumps.

7 
 7. The passage implies that the positive-displacement pump differs from the centrifugal pump in that the positive-displacement pump

(A) is more promising, but it also is more expensive and demands more maintenance
(B) is especially well researched, since it has been used in other settings
(C) involves the use of a single or twin screw that sucks fluid in at one end of the pump
(D) is problematic because it causes rapid shifts from liquid to gas content in crude
(E) involves exposure of many parts of the pump to crude

8 
 8. The passage implies that the current state of technology necessitates that crude be moved to shore

(A) in a multiphase state
(B) in equal proportions of gas to liquid
(C) with small proportions of corrosive material
(D) after having been processed
(E) largely in the form of a liquid

kitipriyanka · Accepted Answer

1. Which one of the following best expresses the main ideas of the passage?

(A) Oil companies are experimenting with technologies that may help diminish the danger to workers from offshore crude processing. - 
processing crude (unprocessed oil or
gas on a platform rather than at facilities onshore
exposes workers to the risks of explosion and to an
unpredictable environment, researchers are
 attempting to diminish the need for human labor
(10) on platforms and even to eliminate platforms
altogether by redesigning two kinds of pumps to
handle crude.   Hold
(B) Oil companies are seeking methods of installing processing facilities underwater. 
 Other researchers are looking at ways of adapting
either kind of pump for use underwater, so that
crude could be moved directly from the sea bottom
(55) to processing facilities onshore, eliminating
platforms.  But this conclusion and not main idea.Eliminate
(C) Researchers are developing several new pumps designed to enhance human labor efficiency in processing facilities. - As A, trying to diminish need of human labor.Eliminate
(D) Researchers are seeking to develop equipment that would preempt the need for processing facilities onshore. - would preempt the need for processing facilities of platforms and not onshore.Eliminate
(E) Researchers are seeking ways to separate liquids from gases in crude in order to enable safer processing.- they are trying ways to have constant proportion of liquid and gases.Eliminate

Hence A

2. The passage supports which one of the following statements about the natural pressure driving the flow of crude?

(A) It is higher than that created by the centrifugal pump.
(B) It is constant, regardless of relative proportions of gas and liquid.
(C) It is able to carry the crude only as far as the wellhead.
(D) It is able to carry the crude to the platform.
(E) It is able to carry the crude to the shore.

"pumps could then be used to boost the natural pressure driving the flow of crude,is sufficient only to bring (15) the crude to the platform"

Hence D

3. Which one of the following best describes the relationship of the second paragraph to the passage as a whole?

(A) It offers concrete detail designed to show that the argument made in the first paragraph is flawed.
(B) It provides detail that expands upon the information presented in the first paragraph.
(C) It enhances the author’s discussion by objectively presenting in detail the pros and cons of a claim made in the first paragraph.
(D) It detracts from the author’s discussion by presenting various problems that qualify the goals presented.
(E) It modifies an observation made in the first paragraph by detailing viewpoints against it.

Fight is between B and C
(B) It provides detail that expands upon the information presented in the first paragraph.
(C) It enhances the author’s discussion by objectively presenting in detail the pros and cons of a claim made in the first paragraph.

2nd para mentions the pros and cons of new designed pumps. But question is asking us to relate 1st and 2nd, and role of 2nd is expansion of the idea presented in 1st.
 Hence B

4. Which one of the following phrases, if substituted for the word “head” in line 47, would LEAST change the meaning of the sentence?

(A) the flow of the crude inside the pump
(B) the volume of oil inside the pump
(C) the volume of gas inside the pump
(D) the speed of the impeller moving the crude
(E) the pressure inside of the pump

Though question is about line 47, but it clearly mention in line 26 about head

This surge in gas content causes
loss of “head,” or pressure inside a pump

Hence E

5. With which one of the following statements regarding offshore platforms would the author most likely agree?

(A) If a reduction of human labor on offshore platforms is achieved, there is no real need to eliminate platforms altogether. - mentioned in para 1 - So there is need to eliminate platforms. This option says opposite. Eliminate
 " researchers are attempting to diminish the need for human labor (10) on platforms and even to eliminate platforms altogether by redesigning two kinds of pumps to handle crude." 
(B) Reducing human labor on offshore platforms is desirable because researchers’ knowledge about the transportation of crude is danerously incomplete. - Author no where mentions about his distrust to researchers knowledge. Eliminate
(C) The dangers involved in working on offshore platforms make their elimination a desirable goal. - mentioned in para 1 -
 " researchers are attempting to diminish the need for human labor (10) on platforms and even to eliminate platforms altogether by redesigning two kinds of pumps to handle crude." 
(D) The positive-displacement pump is the better alternative for researchers, because it would allow them to eliminate platforms altogether. - Last para  "Other researchers are looking at ways of adapting either kind of pump for use underwater, .., eliminating platforms."  Now this is applicable for both pumps and not just positive-displacement pump. Eliminate.
(E) Though researchers have succeeded in reducing human labor on offshore platforms, they think that it would be inadvisable to eliminate platforms altogether, because these platforms have other uses. As mentioned in C,  " researchers are attempting to diminish the need for human labor".  And not yet succeeded. Eliminate
 Hence C

6. Which one of the following can be inferred from the passage about pumps that are currently available to boost the natural pressure of crude?

(A) The efficiency of these pumps depends on there being no gas in the flow of crude. - As above, pressure does require gases. Eliminate
(B) These pumps are more efficient when the crude is less subject to sudden increases in the proportion of gas to liquid.- Hold for 2
(C) A sudden change from solid to liquid in the flow of crude increases the efficiency of these pumps.Eliminate for 1
(D) The proportion of liquid to gas in the flow of crude does not affect the efficiency of these pumps. - It does affect as in 1. Eliminate
(E) A sudden change from liquid to gas in the flow of crude increases the risk of explosion due to rising pressure inside these pumps.-  "But because processing crude (unprocessed oil or gas) on a platform 
exposes workers to the risks of explosion " . This is true but not for natural pressure, it is for crude. And we are inferring about crude. So eliminate

Explanation :
1."Currently, pumps that could boost this natural pressure sufficiently to drive the crude through a pipeline to the shore do not work consistently because of the crude’s content. Crude (20) may consist of oil or natural gas that do not reach the wellhead in constant proportions. The flow of crude oil, for example, can change quickly from 60 percent liquid (25) to 70 percent gas." 
Now we are talking about liquid and gases proportion.

2.Also "Of the two pumps being redesigned, the positive-displacement pump is promising because it
is immune to sudden shifts in the proportion of liquid to gas in the crude mixture. "
Also, what is improving as part of new design of pump is " sudden shifts in the proportion of liquid to gas in the crude mixture"

Hence B

7. The passage implies that the positive-displacement pump differs from the centrifugal pump in that the positive-displacement pump

POE
(A) is more promising, but it also is more expensive and demands more maintenance - Alluring but not true because of "demands more maintenance". Eliminate
(B) is especially well researched, since it has been used in other settings - Pros and Cons of positive dis. pump is due its new design and not settings. Eliminate.
(C) involves the use of a single or twin screw that sucks fluid in at one end of the pump - "single or twin screw (35) pushing the fluid from one end of the pump to the other". NO mention about sucking fluid. Eliminate
(D) is problematic because it causes rapid shifts from liquid to gas content in crude - "promising because it is immune to sudden shifts in the proportion of liquid to gas in the crude mixture" Eliminate
(E) involves exposure of many parts of the pump to crude - "brings crude into close contact with most parts of the pump". Hold

Explanation :
"positive-displacement pump is promising because it is immune to sudden shifts in the proportion of liquid to gas in the crude mixture. But the pump’s design, which consists of a single or twin screw (35) pushing the fluid from one end of the pump to the other, brings crude into close contact with most parts of the pump, and thus requires that it be made of expensive corrosion-resistant material.
The alternative is the centrifugal pump, ... Although this pump has a proven design and has worked for years with little maintenance in waste-disposal plants,"

Now above says positive-displacement pump is promising and expensive and involves crude into close contact with most parts of the pump.
And centrifugal pump needs little maintenance in waste-disposal plants. 
Nowhere it mentions how much maintenance positive-displacement pump requires and how it works in waste-disposal plants.

Hence E

8. The passage implies that the current state of technology necessitates that crude be moved to shore

(A) in a multiphase state
(B) in equal proportions of gas to liquid
(C) with small proportions of corrosive material
(D) after having been processed
(E) largely in the form of a liquid

" Oil companies need offshore platforms primarily because the oil or natural gas the companies extract
from the ocean floor has to be processed before pumps can be used to move the substances ashore "

Hence D

Skywalker18 · Answer

All correct except question 1 in 14 mins, including 4 mins 30 seconds to read

1. Which one of the following best expresses the main ideas of the passage?
(A) Oil companies are experimenting with technologies that may help diminish the danger to workers from offshore crude processing. 
(D) Researchers are seeking to develop equipment that would preempt the need for processing facilities onshore.

I was in a fix between option A and D and ended up choosing option D. In case of option A, I wasn't very sure whether these researchers work for the Oil companies and thus I rejected option A.
Is option D incorrect because of 'would' as we are not sure about the success of the research?

But because processing crude (unprocessed oil or gas on a platform rather than at facilities onshore exposes workers to the risks of explosion and to an unpredictable environment, researchers are attempting to diminish the need for human labor on platforms and even to eliminate platforms altogether by redesigning two kinds of pumps to handle crude

AjiteshArun  ,  GMATNinja  ,  MagooshExpert  ,  GMATGuruNY  ,  VeritasPrepBrian  ,  MartyTargetTestPrep  ,  DmitryFarber  ,  VeritasKarishma  ,  generis  ,  jennpt  , other experts

generis · Answer

Skywalker18  , your time and accuracy are outstanding; this passage is technical and dry.

LSAC and GMAC test writers are good at catching people with a combination of phrases that negate 
("preempt the need for") and words that we have just seen in the passage. We let down our guard.

Option D is incorrect because it is exactly the  opposite  of what the passage says.

Researchers are trying to preempt (to  prevent ) the need for  platforms ,
not the need for onshore facilities.

Oil companies and researchers want to preempt the need for platforms, in fact,
so that crude  can  get directly to  onshore facilities , because onshore facilities are safer for workers than platforms are.

From Paragraph 1, second sentence):

"But because processing crude (unprocessed oil or
gas)  on a platform   rather than at facilities onshore 
 exposes workers to the risks of explosion and to an unpredictable environment  . . ."

The passage also indicates that researchers are trying to get human beings off of platforms:
". . . researchers are attempting to diminish the need for human labor on platforms and  even to eliminate  platforms 
altogether  . . ."

The passage then mentions that researchers are looking for ways to get crude oil directly to shore—meaning, from sea bottom to shore  without a platform  in the middle. See the examples immediately below.
 
• one pump needs redesign because it "  . . . transport the crude mixture through the pipeline and    to the shore "   (Paragraph 1, last sentence)

• "other researchers are looking at ways of adapting
either kind of pump for use underwater, so that  crude could be moved directly from the sea bottom
 to processing facilities onshore ,  eliminating
platforms ."  (Paragraph 3, last sentence)

Platforms need to go away, not onshore facilities.

Whoops. It happens. 
At the moment, half of people have chosen A, but D is the next favorite; one-fourth
of people have chosen D.

I hope that helps.

GMATNinja · Answer

There is one little word in (D) that makes it absolutely incorrect:  onshore .

Currently, the crude "has to be processed before pumps can be used to move the substances  ashore ." So, currently, the crude has to be processed OFFSHORE (on a platform) before it can be moved onshore. The goal of the current research is to eliminate the need for this OFFSHORE processing. The researchers are NOT trying to develop equipment that would preempt the need for ONSHORE processing facilities. In fact, they WANT the crude to be processed onshore, where the process is safer.

So (D) has to go!

auradediligodo · Answer

Hi,
Took 18 minutes and got 6/8 correct. It took 6 minutes for reading, writing down paragraphs summaries and main point formulation.
here is my detailed analysis:

P1: A problem related to Oil companies is described and two solutions to it are presented
P2: The two solutions mentioned are further described and a problem related to each is presented
P3: Which aspects researchers are trying to improve

MP: to present a problem related to oil companies and to discuss solutions and improvements to it

1. Which one of the following best expresses the main ideas of the passage?

Prethinking:  refer to the main point formulation

(A) Oil companies are experimenting with technologies that may help diminish the danger to workers from offshore crude processing.  my MP is worded differently but: Problem=danger, solutions and improvements=experimenting with technologies 
(B) Oil companies are seeking methods of installing processing facilities underwater.  the underwater side is mentioned in the last paragraph and hence this AC is partial scope 
(C) Researchers are developing several new pumps designed to enhance human labor efficiency in processing facilities.  note that the goal is to reduce the danger associated and not the labor efficiency; inconsistent 
(D) Researchers are seeking to develop equipment that would preempt the need for processing facilities onshore.  onshore here makes this AC inconsistent; the goal in fact is to process OFFSHORE 
(E) Researchers are seeking ways to separate liquids from gases in crude in order to enable safer processing.  not mentioned hence out of scope

2. The passage supports which one of the following statements about the natural pressure driving the flow of crude?

prethinking:  refer to P1 and specifically to this portion: These pumps could then be used to
boost the natural pressure driving the flow of
crude, which, by itself, is sufficient only to bring
(15) the crude to the platform, located just above the
wellhead
  
(A) It is higher than that created by the centrifugal pump.  not mentioned, hence out of scope 
(B) It is constant, regardless of relative proportions of gas and liquid.  no mention so out of scope 
(C) It is able to carry the crude only as far as the wellhead.  if you refer to the portion reported in the rethinking you can see that by itself the natural pressure arrives a little above the wellhead. so this option choice is incorrect 
(D) It is able to carry the crude to the platform.  in line with our prethinking 
(E) It is able to carry the crude to the shore.  no mention so out of scope

3. Which one of the following best describes the relationship of the second paragraph to the passage as a whole?

Prethinking:  the second paragraphs describes in detail the solutions presented before in the first paragraph so  it gives details presented in the preceding paragraph

(A) It offers concrete detail designed to show that the argument made in the first paragraph is flawed.  to show that the first paragraph is flawed is not the purpose of P2. Flaws are mentioned in the form of describing some limits that the two solutions have 
(B) It provides detail that expands upon the information presented in the first paragraph.  in line with our rethinking, correct 
(C) It enhances the author’s discussion by objectively presenting in detail the pros and cons of a claim made in the first paragraph.  P2 doesn't describe in detail a claim but two solutions and their mechanisms along with 2 drawbacks. incorrect 
(D) It detracts from the author’s discussion by presenting various problems that qualify the goals presented.  here  detracts  just doesn't work and solutions are presented rather than problems  
(E) It modifies an observation made in the first paragraph by detailing viewpoints against it.  no modification is made and no viewpoints against the observation are made

4. Which one of the following phrases, if substituted for the word “head” in line 47, would LEAST change the meaning of the sentence?

Prethinking:  I found this question statement quite deceiving because it leads you to work on your answer choice around the line 47 BUT you should focus on the meaning of head and you should not limit your analysis around those lines. I fact the word  head  is mentioned in P1 where:  This surge in gas content causes
loss of “head,” or pressure inside a pump, . this makes our work of selection really easy

(A) the flow of the crude inside the pump - not in line with our prethinking 
(B) the volume of oil inside the pump  not in line with our prethinking 
(C) the volume of gas inside the pump  not in line with our prethinking 
(D) the speed of the impeller moving the crude  not in line with our prethinking 
(E) the pressure inside of the pump  correct

5. With which one of the following statements regarding offshore platforms would the author most likely agree?

Prethinking:  this question statement is too general for a specific prethinking but probably our focus will be on P1

(A) If a reduction of human labor on offshore platforms is achieved, there is no real need to eliminate platforms altogether.  this relation cause-effect is never mentioned in the passage, hence out of scope 
(B) Reducing human labor on offshore platforms is desirable because researchers’ knowledge about the transportation of crude is danerously incomplete.  what is dangerous is the environment of offshore platform and not the incomplete knowledge, hence inconsistent 
(C) The dangers involved in working on offshore platforms make their elimination a desirable goal.  correct as mentioned in the first part of P1 
(D) The positive-displacement pump is the better alternative for researchers, because it would allow them to eliminate platforms altogether.  nowhere the PDP is awarded as better that all other pumps and moreover it doesn't eliminate the need of platform all together, hence out of scope 
(E) Though researchers have succeeded in reducing human labor on offshore platforms, they think that it would be inadvisable to eliminate platforms altogether, because these platforms have other uses.  other uses are not mentioned. plus in the last paragraph it is mentioned that researchers are working on a way to eliminate definitely platforms. So why to work on this angle if researchers want to keep platforms?!. Incorrect

6. Which one of the following can be inferred from the passage about pumps that are currently available to boost the natural pressure of crude?

prethinking:  here we can make several inferences. For example we can infer that currently available pumps can not work efficiently when oil is in a multiphase state OR current pumps can not deal with fast shifts in the concentration of oil
 
(A) The efficiency of these pumps depends on there being no gas in the flow of crude.  too extreme. nowhere it is said that current pumps need no gas present to function 
(B) These pumps are more efficient when the crude is less subject to sudden increases in the proportion of gas to liquid.  correct and in line with our prethinking 
(C) A sudden change from solid to liquid in the flow of crude increases the efficiency of these pumps.  opposite! pumps don't work well in this case 
(D) The proportion of liquid to gas in the flow of crude does not affect the efficiency of these pumps.  nowhere this can be inferred. note that the example made in paragraph one has the purpose to show what happens after a sudden chance in proportion 
(E) A sudden change from liquid to gas in the flow of crude increases the risk of explosion due to rising pressure inside these pumps.  inconsistent. the sudden chance makes the pump not working efficiently. risk of explosion is not mentioned

7. The passage implies that the positive-displacement pump differs from the centrifugal pump in that the positive-displacement pump

prethinking:  refer to the second paragraph here.one main difference is that the PDP is promising and probably new while the CP was used in other fields. other features such as the" twin screw" or "swirl of its impeller" should not be considered as differences since we do not have enough information to consider them as such

(A) is more promising, but it also is more expensive and demands more maintenance   the word more here is wrong and never mentioned. also it is never stated that it demands less mantainance or that is more expensive 
(B) is especially well researched, since it has been used in other settings  I would say opposite here since it is the CP that was used in other fields 
(C) involves the use of a single or twin screw that sucks fluid in at one end of the pump  we do not know for sure that this is a difference hence incorrect 
(D) is problematic because it causes rapid shifts from liquid to gas content in crude  opposite here. this pump is immune to these shifts 
(E) involves exposure of many parts of the pump to crude  although not in line with the prethinking this is a drawback of the PDP and it is likely that it does not regard as well the CP since it was already studied and used in other fields

8. The passage implies that the current state of technology necessitates that crude be moved to shore

Prethinking:  refer to the first lines of P1. It says that the crude must be processed before being moved ashore

(A) in a multiphase state  nowhere mentioned 
(B) in equal proportions of gas to liquid  not mentioned as a requirement 
(C) with small proportions of corrosive material  corrosive material is a drawback of the PDP and for sure not a requirement 
(D) after having been processed  correct since in line with our prethinking 
(E) largely in the form of a liquid  not mentioned hence incorrect

Harsh2111s · Answer

VeritasKarishma   GMATNinja 
As per passage option "E" can't be true since it is mentioned that both comes in contact with crude and thus can't be a difference.

"But the pump’s design, which consists of a single or twin screw pushing the fluid from one end of the pump to the other, brings crude into close contact with most parts of the pump, and thus requires that it be made of expensive corrosion-resistant material."
"The alternative is the centrifugal pump, which has a rotating impeller that sucks fluid in at one end and forces fluid out at the other.
Fluid comes in contact with parts of centrifugal pump.
(Crude is a mixture of unprocesses oil or gas, and fluid is a mixture of liquid and gas by definition.)
Please explain how E can be true.

SajjadAhmad , Can you share official solution for this question.

Sajjad1994 · Answer

Hello  Harsh2111s  this is not an official explanation but let me know if it make any sense

Explanation

7. The passage implies that the positive-displacement pump differs from the centrifugal pump in that the positive-displacement pump

Difficulty Level:   700

Explanation

Appears to be a detail question, but has as much to do with inference and tone as knowing the specifics about each pump.  (E)  describes the downside of the p-d pump and, inferably, the reason that the c-pump is seen as  “the alternative”  with the  “proven design” (see lines 33-41).

(A)  is right in noting that the c-pump is cheaper and lower maintenance, but wrong in citing the p-d pump as  “more promising.”  The author makes no such assessment. Each pump described has its pros and cons.

(B) , too, errs by implying that the author favors the p-d pump over the other one. Also, it’s the c-pump, not the p-d pump, that  “has been used in other settings” (lines 41-43).

(C)  Boy, did students pick this one. Two problems, either of which is enough to disqualify it: (1) The p-d pump does in fact have a single or twin screw, but there’s no evidence that such a device is unique to that pump; maybe the c-pump has something like it as well. So this isn’t a clear-cut point of difference. (2) The only device mentioned in the passage as  “sucking fluid in at one end”  is the c-pump. We can’t be sure that that’s what the screws do in the p-d pump. (In fact, from the sound of it, the p-d pump does nothing of the kind.) Again—not a clear-cut point of difference.

(D)  The liquid/gas shifts, which are of course discussed a paragraph earlier, are common to all crude and affect both pumps under redesign.

Answer: E

adstudy · Answer

Hi Harsh2111s As per me, the below excerpt from the passage may help you answer how E can be successfuly deduced. Of the two pumps being redesigned, the positive-displacement pump is promising because it is immune to sudden shifts in the proportion of liquid to gas in the crude mixture. But the pump’s design, which consists of a single or twin screw (35) pushing the fluid from one end of the pump to the other, brings crude into close contact with most parts of the pump, and thus requires that it be made of expensive corrosion-resistant material . The alternative is the centrifugal pump , which has a (40) rotating impeller that sucks fluid in at one end and forces fluid out at the other. Although this pump has a proven design and has worked for years with little maintenance in waste-disposal plants, researchers have discovered that because the swirl (45) of its impeller separates gas out from the oil that normally accompanies it, significant reductions in head can occur as it operates. From the red part we can deduce that crude is damaging to the parts of a pump on exposure. Hence in the first pump as there is more exposure, more damage is noted. Whereas when we pass the same damaging crude through the second pump, the passage says that it requires little maintenance over the years as highlighted in blue . Therefore we can deduce that the second pump is having a mechanism to prevent its parts from exposure, in turn, increasing its maintenance period. This leads us to Option E . This is my take on the Question. Although waiting for the experts to weigh in their analysis on the same.

KarishmaB · Answer

The question says that passage 'implies' so the difference would be an implication of what is given in the passage.

PDP's design brings crude into close contact with most
parts of the pump, and thus requires that it be
made of expensive corrosion-resistant material.

...
Research in the development of these pumps is
focused mainly on trying to reduce the cost of the PDP

CP has a proven design and has worked for years with
little maintenance in waste-disposal plants  (implied that it's design is such that cost n maintenance is lower. This can happen only if the pump does not bring crude into close contact with most parts else it would need to be made of expensive corrosion resistant material too.)
...
 Research in the development of these pumps is
focused mainly on ... attempting to
make the CP more tolerant of gas.

PDP is expensive and CP is not tolerant to gas. 
PDP has exposure to many parts of the pump while CP does not. 
Answer (E) is correct.

The only other option worth noting is (A) but that says PDP is "more promising" which is not implied anywhere.

Option (C) is not correct because we don't know the exact design of CP.

gmat1393 · Answer

Hi  VeritasKarishma

Don't these lines imply that PDP is more promising than the other one?

KarishmaB · Answer

This is what it says:
Of the two, X is promising because of A but it has B problem. The other one, Y is good because of C but it has A'. 
Finally, which factor counts more and what makes one 'more promising' over the other, we can't really say.

DanTe02 · Answer

VeritasKarishma  
 
Logically Of the two X is promising is not the same thing as Of the Two, X is more promising. The passage perhaps is tricky because its very easy to miss the word "more"
But how do we not know that perhaps the centrifugal pumps do not expose most of their parts and perhaps have low maintenance due to something else

KarishmaB · Answer

We are given that the design of the two pumps is different. Problem with one is that it is expensive but that is not the problem with the other. We are given why PDP's are expensive - because their parts are exposed to oil. Since CGs are not expensive, their parts must not be exposed. 
It may not be given to us directly in the passage but the passage does imply it.

Oil companies need offshore platforms primarily because the oil or nat

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Oil companies need offshore platforms primarily because the oil or nat

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