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Questions 19-20 are based on the following. Blood banks will

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Questions 19-20 are based on the following. Blood banks will  [#permalink]

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New post 17 Aug 2009, 09:33
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A
B
C
D
E

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Questions 19-20 are based on the following.

Blood banks will shortly start to screen all donors for NANB hepatitis. Although the new screening tests are estimated to disqualify up to 5 percent of all prospective blood donors, they will still miss two-thirds of donors carrying NANB hepatitis. Therefore, about 10 percent of actual donors will still supply NANB-contaminated blood.

19. The argument above depends on which of the following assumptions?

(A) Donors carrying NANB hepatitis do not, in a large percentage of cases, carry other infections for which reliable screening tests are routinely performed.
(B) Donors carrying NANB hepatitis do not, in a large percentage of cases, develop the disease themselves at any point.
(C) The estimate of the number of donors who would be disqualified by tests for NANB hepatitis is an underestimate.
(D) The incidence of NANB hepatitis is lower among the potential blood donors than it is in the population at large.
(E) The donors who will still supply NANB-contaminated blood will donate blood at the average frequency for all donors.

20. Which of the following inferences about the consequences of instituting the new tests is best supported by the passage above?

(A) The incidence of new cases of NANB hepatitis is likely to go up by 10 percent.
(B) Donations made by patients specifically for their own use are likely to become less frequent.
(C) The demand for blood from blood banks is likely to fluctuate more strongly.
(D) The blood supplies available from blood banks are likely to go down.
(E) The number of prospective first-time donors is likely to go up by 5 percent.

Spoiler: :: OA
19's A, 20's D
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New post 18 Aug 2009, 02:25
C and A well I do not have any explanation cause I just eliminated the other choices. I may be wrong especially in the first one because stuck between C and B sorry :(
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Re: Questions 19-20 are based on the following. Blood banks will  [#permalink]

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New post 02 Sep 2009, 08:17
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Q1 A
The author is saying that 2/3rd of the cases of NANB will end up donating blood because they won't be detected by the screen. If any of those 2/3rd cases were to have concomitant diseases that could be detected by the donor-screen, the total no. of such cases of NANB donating blood would go down. The author is obviously assuming that that is not the case.

Q2 E
Let x=potential donors.
Let y=actual donors.
Let z=NANB cases that have come to donate blood.

5x/100 = z/3; x=20z/3

10y/100 = 2z/3; y=20z/3
Therefore, x=y, i.e., potential donors=actual donors.
So, if the potential donors lose 5% of their population due to NANB+ screen, yet they are equal in number to the actual donors, then the potential donors must have increased by 5% population.
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Re: Questions 19-20 are based on the following. Blood banks will  [#permalink]

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New post 29 Nov 2009, 11:26
apramanik wrote:
Questions 19-20 are based on the following.
Blood banks will shortly start to screen all donors for NANB hepatitis. Although the new screening tests are estimated to disqualify up to 5 percent of all prospective blood donors, they will still miss two-thirds of donors carrying NANB hepatitis. Therefore, about 10 percent of actual donors will still supply NANB-contaminated blood.
19. The argument above depends on which of the following assumptions?
(A) Donors carrying NANB hepatitis do not, in a large percentage of cases, carry other infections for which reliable screening tests are routinely performed.
(B) Donors carrying NANB hepatitis do not, in a large percentage of cases, develop the disease themselves at any point.
(C) The estimate of the number of donors who would be disqualified by tests for NANB hepatitis is an underestimate.
(D) The incidence of NANB hepatitis is lower among the potential blood donors than it is in the population at large.
(E) The donors who will still supply NANB-contaminated blood will donate blood at the average frequency for all donors.
20. Which of the following inferences about the consequences of instituting the new tests is best supported by the passage above?
(A) The incidence of new cases of NANB hepatitis is likely to go up by 10 percent.
(B) Donations made by patients specifically for their own use are likely to become less frequent.
(C) The demand for blood from blood banks is likely to fluctuate more strongly.
(D) The blood supplies available from blood banks are likely to go down.
(E) The number of prospective first-time donors is likely to go up by 5 percent.

Firstly, Need Explanation. Secondly, Need Explanation and Thirdly Need Explanation.


For the first question, I pick A as my answer. I chose A because it implies that the screening test could be made to disqualify people carrying different diseases other than NANB hepatitis. Option A says "other infections for which reliable screening tests are routinely performed." If that's the case, then it makes sense why the screening test can miss 2/3 of the people carrying the NANB hepatitis.

For the second question, I pick A. Here's my approach:
A) The "likely" makes this option uncertainly, making it an attractive option. As 2/3 (which is 66%) of the donars will still carry the NANB hepatitis, then it is realistic to expect the new cases of this disease to rise by 10% if not more.
B) We have no idea about the frequency of donations. So this option is out.
C) Nothing was discussed in the argument about the flunctuation of the demand of blood. We only know about the new screening test and the likely outcome of donars still carrying the NANB hepatitus even after the new screening test.
D) Nothing was discussed in the argument about the trend of blood supplies.
E) Nothing was discussed in the argument about the number of prospective first-time donars.

So my answer for the second question remains to be A.
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Re: Questions 19-20 are based on the following. Blood banks will  [#permalink]

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New post 29 Nov 2009, 13:36
apramanik wrote:
Questions 19-20 are based on the following.
Blood banks will shortly start to screen all donors for NANB hepatitis. Although the new screening tests are estimated to disqualify up to 5 percent of all prospective blood donors, they will still miss two-thirds of donors carrying NANB hepatitis. Therefore, about 10 percent of actual donors will still supply NANB-contaminated blood.
19. The argument above depends on which of the following assumptions?
(A) Donors carrying NANB hepatitis do not, in a large percentage of cases, carry other infections for which reliable screening tests are routinely performed.
(B) Donors carrying NANB hepatitis do not, in a large percentage of cases, develop the disease themselves at any point.
(C) The estimate of the number of donors who would be disqualified by tests for NANB hepatitis is an underestimate.
(D) The incidence of NANB hepatitis is lower among the potential blood donors than it is in the population at large.
(E) The donors who will still supply NANB-contaminated blood will donate blood at the average frequency for all donors.
20. Which of the following inferences about the consequences of instituting the new tests is best supported by the passage above?
(A) The incidence of new cases of NANB hepatitis is likely to go up by 10 percent.
(B) Donations made by patients specifically for their own use are likely to become less frequent.
(C) The demand for blood from blood banks is likely to fluctuate more strongly.
(D) The blood supplies available from blood banks are likely to go down.
(E) The number of prospective first-time donors is likely to go up by 5 percent.

Firstly, Need Explanation. Secondly, Need Explanation and Thirdly Need Explanation.



Premise-1: Blood banks will shortly start to screen all donors for NANB hepatitis.
Premise-2: Although the new screening tests are estimated to disqualify up to 5 percent of all prospective blood donors, they will still miss two-thirds of donors carrying NANB hepatitis.
Conclusion: Therefore, about 10 percent of actual donors will still supply NANB-contaminated blood.

1) Assumption for the premises to reach that conclusion is what is asked.
A) There is no discussion about other infections and whether donors will probably carry them or not or whether appropriate tests are conducted or not, in the passage. So Incorrect option, does not bridge the gap between the premises and conclusion.
B) Do donors develop the disease themselves or not either does not explain possible connection between the premises and the conclusion that 10% will still supply the contaminated blood. So again Incorrect.
C) We can't comment if the percentage of donors disqualified is an underestimate or not. Even if so, it is not an assumption that could bridge the gap between the premises and the conclusion.
D) The incidence of NANB among potential donors being higher than the population at large cannot be commented upon, neither does it bridge the gap so Incorrect again.
E) Correct answer. If let's say NANB donors who are either aware or unaware of the disease and it's risks and are still active donors turn up for the blood donation activity, then the figures and percentages and everything discussed at large in the passage can make some sense and the conclusion is valid. So for the passage to be true and wholesome, first of all NANB donors should be active donors and turn up like the general population of donors. The average rate of donations like any previous statistical data should persist. This is the underlying assumption for the entire passage as a whole.

2) What can be understood from the premises? This need not be the conclusion. An inference is what is understood from relevant facts, a conclusion can be what is finally driven given certain considerations.
A) Incidence of new cases cannot be commented upon with the info from the premises. Don't generalize that 2/3 of donated blood is still contaminated and so can be used. What if there are tests conducted before offering the blood to another patient? So Incorrect option.
B) Donations for own use will become less, how can this ever be understood from the premises?
C) The demand for blood from blood banks will fluctuate strongly, how in God's world can someone deduce fluctuation of demand from the given info?
D) Correct answer. Consider 100 donors that include 50 NANB carriers for numbers sake. 5% will be disqualified - total donors comes down to 95 and potential carriers are now 45. Still 2/3 of NANB carriers may not be detected, so out of 45 at least 30 might donate, still a part of 95 only. Overall, if 100 bottles were collected on average, due to disqualification of 5%, the availability of donated blood is reducing in the blood bank.
E) prospective first-time donors, Gawd, am tired of typing anymore!!!! Anyways, Incorrect.
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New post 29 Nov 2009, 16:21
BarneyStinson wrote:
apramanik wrote:
Questions 19-20 are based on the following.
Blood banks will shortly start to screen all donors for NANB hepatitis. Although the new screening tests are estimated to disqualify up to 5 percent of all prospective blood donors, they will still miss two-thirds of donors carrying NANB hepatitis. Therefore, about 10 percent of actual donors will still supply NANB-contaminated blood.
19. The argument above depends on which of the following assumptions?
(A) Donors carrying NANB hepatitis do not, in a large percentage of cases, carry other infections for which reliable screening tests are routinely performed.
(B) Donors carrying NANB hepatitis do not, in a large percentage of cases, develop the disease themselves at any point.
(C) The estimate of the number of donors who would be disqualified by tests for NANB hepatitis is an underestimate.
(D) The incidence of NANB hepatitis is lower among the potential blood donors than it is in the population at large.
(E) The donors who will still supply NANB-contaminated blood will donate blood at the average frequency for all donors.
20. Which of the following inferences about the consequences of instituting the new tests is best supported by the passage above?
(A) The incidence of new cases of NANB hepatitis is likely to go up by 10 percent.
(B) Donations made by patients specifically for their own use are likely to become less frequent.
(C) The demand for blood from blood banks is likely to fluctuate more strongly.
(D) The blood supplies available from blood banks are likely to go down.
(E) The number of prospective first-time donors is likely to go up by 5 percent.

Firstly, Need Explanation. Secondly, Need Explanation and Thirdly Need Explanation.



Premise-1: Blood banks will shortly start to screen all donors for NANB hepatitis.
Premise-2: Although the new screening tests are estimated to disqualify up to 5 percent of all prospective blood donors, they will still miss two-thirds of donors carrying NANB hepatitis.
Conclusion: Therefore, about 10 percent of actual donors will still supply NANB-contaminated blood.

1) Assumption for the premises to reach that conclusion is what is asked.
A) There is no discussion about other infections and whether donors will probably carry them or not or whether appropriate tests are conducted or not, in the passage. So Incorrect option, does not bridge the gap between the premises and conclusion.
B) Do donors develop the disease themselves or not either does not explain possible connection between the premises and the conclusion that 10% will still supply the contaminated blood. So again Incorrect.
C) We can't comment if the percentage of donors disqualified is an underestimate or not. Even if so, it is not an assumption that could bridge the gap between the premises and the conclusion.
D) The incidence of NANB among potential donors being higher than the population at large cannot be commented upon, neither does it bridge the gap so Incorrect again.
E) Correct answer. If let's say NANB donors who are either aware or unaware of the disease and it's risks and are still active donors turn up for the blood donation activity, then the figures and percentages and everything discussed at large in the passage can make some sense and the conclusion is valid. So for the passage to be true and wholesome, first of all NANB donors should be active donors and turn up like the general population of donors. The average rate of donations like any previous statistical data should persist. This is the underlying assumption for the entire passage as a whole.

2) What can be understood from the premises? This need not be the conclusion. An inference is what is understood from relevant facts, a conclusion can be what is finally driven given certain considerations.
A) Incidence of new cases cannot be commented upon with the info from the premises. Don't generalize that 2/3 of donated blood is still contaminated and so can be used. What if there are tests conducted before offering the blood to another patient? So Incorrect option.
B) Donations for own use will become less, how can this ever be understood from the premises?
C) The demand for blood from blood banks will fluctuate strongly, how in God's world can someone deduce fluctuation of demand from the given info?
D) Correct answer. Consider 100 donors that include 50 NANB carriers for numbers sake. 5% will be disqualified - total donors comes down to 95 and potential carriers are now 45. Still 2/3 of NANB carriers may not be detected, so out of 45 at least 30 might donate, still a part of 95 only. Overall, if 100 bottles were collected on average, due to disqualification of 5%, the availability of donated blood is reducing in the blood bank.
E) prospective first-time donors, Gawd, am tired of typing anymore!!!! Anyways, Incorrect.


Great explaination! I agree with your answers 100%. On the second question, however, isn't option D the correct answer mainly because of the fact that 5 percent of all prospective blood donors are estimated to be disqualified, leading to the inference that the blood supplies are likely to go down? I think this bit of information is enough to choose option D without getting into all these details. What do you think?

Thanks!
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Re: Questions 19-20 are based on the following. Blood banks will  [#permalink]

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New post 01 Dec 2009, 02:26
Q1. Pick A.
It's a very common assumption for GMAT.
It could be that tests disqualify up to 5% not due to NANB, but due to other infections. Therefore conclusion will fall apart.

Q2. Pick D. Accurate inference
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New post 01 Dec 2009, 03:52
bsv180985 wrote:
Q1. Pick A.
It's a very common assumption for GMAT.
It could be that tests disqualify up to 5% not due to NANB, but due to other infections. Therefore conclusion will fall apart.

Q2. Pick D. Accurate inference


What you said for the first question is true, but the assumption should make the conclusion true and believable rather than make it fall apart. The conclusion here says, "about 10 percent of actual donors will still supply NANB-contaminated blood." How can the author conclude such a thing if he assumes something that will make his conclusion wrong? Option A is talking about a specific screening test, it's talking about the reliable ones. We don't know whether the screening test mentioned in the argument is reliable. We only know that these screening tests are new. So we can't be certain that option A is talking about the same screening tests that the argument was talking about. See my point?
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New post 01 Dec 2009, 04:27
May be I miss discrepancy in screening tests in argument and in A. But I do think that these are the same tests.

You're right, conclusion shouldn't be fallen apart. It should be supported. I mean, if we neglect information in "A", conclusion will fall apart. Futhermore, if we assume A, conclusion will be supported.

Premise1. 5% - disqualified
Premise2. 2/3 still with NANB
Conclusion. about 10 percent of actual donors will still supply NANB-contaminated blood

In argument, it's well known that about 15% of donors have NANB
Ok, if 5% = 1/3, then 2/3=10%. It's ok.

But, we must assume that all 5% were people with NANB.

Screening tests could disqualify people with another infection, who have no NANB. If so, it's wrong to conclude that 10% still with NANB - it should be greater.

Once again, i belive that tests in argument and in ans A are the same.


GMATFIGHTER wrote:
bsv180985 wrote:
Q1. Pick A.
It's a very common assumption for GMAT.
It could be that tests disqualify up to 5% not due to NANB, but due to other infections. Therefore conclusion will fall apart.

Q2. Pick D. Accurate inference


What you said for the first question is true, but the assumption should make the conclusion true and believable rather than make it fall apart. The conclusion here says, "about 10 percent of actual donors will still supply NANB-contaminated blood." How can the author conclude such a thing if he assumes something that will make his conclusion wrong? Option A is talking about a specific screening test, it's talking about the reliable ones. We don't know whether the screening test mentioned in the argument is reliable. We only know that these screening tests are new. So we can't be certain that option A is talking about the same screening tests that the argument was talking about. See my point?
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New post 01 Dec 2009, 05:43
hmm...this is interesting. Well, let me comment on some of your points:

You mentioned here, "But, we must assume that all 5% were people with NANB." My question here to you is that why must you assume that?? The trick here is not to make any assumptions on behalf of the author. You could be right or you could be wrong about this, but until you can get hard evidence that bridges your claim that 5% were people with NANB, you should not make this claim yourself. I think your job here is to make all the connections to prove your claim. If I ask you "how do you know that the 5% were people with NANB?" If you answer me, "This is what I'm sure of" without giving me facts, then you should be aware that this claim is not yet 100% valid.

Also, isn't option A going out of scope when it's talking about the reliable screening tests rather than the new screening tests?




bsv180985 wrote:
May be I miss discrepancy in screening tests in argument and in A. But I do think that these are the same tests.

You're right, conclusion shouldn't be fallen apart. It should be supported. I mean, if we neglect information in "A", conclusion will fall apart. Futhermore, if we assume A, conclusion will be supported.

Premise1. 5% - disqualified
Premise2. 2/3 still with NANB
Conclusion. about 10 percent of actual donors will still supply NANB-contaminated blood

In argument, it's well known that about 15% of donors have NANB
Ok, if 5% = 1/3, then 2/3=10%. It's ok.

But, we must assume that all 5% were people with NANB.

Screening tests could disqualify people with another infection, who have no NANB. If so, it's wrong to conclude that 10% still with NANB - it should be greater.

Once again, i belive that tests in argument and in ans A are the same.


GMATFIGHTER wrote:
bsv180985 wrote:
Q1. Pick A.
It's a very common assumption for GMAT.
It could be that tests disqualify up to 5% not due to NANB, but due to other infections. Therefore conclusion will fall apart.

Q2. Pick D. Accurate inference


What you said for the first question is true, but the assumption should make the conclusion true and believable rather than make it fall apart. The conclusion here says, "about 10 percent of actual donors will still supply NANB-contaminated blood." How can the author conclude such a thing if he assumes something that will make his conclusion wrong? Option A is talking about a specific screening test, it's talking about the reliable ones. We don't know whether the screening test mentioned in the argument is reliable. We only know that these screening tests are new. So we can't be certain that option A is talking about the same screening tests that the argument was talking about. See my point?
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New post Updated on: 01 Dec 2009, 06:52
Ok, let me try to explain in other way.

In short:
1. 5% disqualified
2. 2/3 still have NANB
3. Conclusion 10% have NANB

Right? Notice that 2=3 . 2/3 of NANB infected = 10%
Hence, 1/3 = 5% what is equal to 1. Hence, we have to be sure that disqualified 5% were exactly those with NANB (those 1/3).

In argument NO info that screening tests aimed ONLY at NANB infected. Hence, tests could disqualify non-NANB infected. If in disqualified 5% 2% were NANB+ and 3% non-NANB, then
2% not equal to 1/3.

Fighter, I'm not sure that "new screening tests" = "reliable screening tests". But I think it's true.

Can smb share OA and OE?


GMATFIGHTER wrote:
hmm...this is interesting. Well, let me comment on some of your points:

You mentioned here, "But, we must assume that all 5% were people with NANB." My question here to you is that why must you assume that?? The trick here is not to make any assumptions on behalf of the author. You could be right or you could be wrong about this, but until you can get hard evidence that bridges your claim that 5% were people with NANB, you should not make this claim yourself. I think your job here is to make all the connections to prove your claim. If I ask you "how do you know that the 5% were people with NANB?" If you answer me, "This is what I'm sure of" without giving me facts, then you should be aware that this claim is not yet 100% valid.

Also, isn't option A going out of scope when it's talking about the reliable screening tests rather than the new screening tests?

Originally posted by bsv180985 on 01 Dec 2009, 06:29.
Last edited by bsv180985 on 01 Dec 2009, 06:52, edited 1 time in total.
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New post 01 Dec 2009, 06:37
BTW, i see you initially opt A as an answer?)) What makes you change decision?

GMATFIGHTER wrote:
For the first question, I pick A as my answer. I chose A because it implies that the screening test could be made to disqualify people carrying different diseases other than NANB hepatitis. Option A says "other infections for which reliable screening tests are routinely performed." If that's the case, then it makes sense why the screening test can miss 2/3 of the people carrying the NANB hepatitis.
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New post 01 Dec 2009, 06:42
bsv180985 wrote:
BTW, i see you initially opt A as an answer?)) What makes you change decision?

GMATFIGHTER wrote:
For the first question, I pick A as my answer. I chose A because it implies that the screening test could be made to disqualify people carrying different diseases other than NANB hepatitis. Option A says "other infections for which reliable screening tests are routinely performed." If that's the case, then it makes sense why the screening test can miss 2/3 of the people carrying the NANB hepatitis.


Yes you're right, I initially chose A as my answer because I missed "reliable screening test." But after noticing that thanks to BarneyStinson, I corrected myself and rather agree that option E should be the answer.
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New post 01 Dec 2009, 07:50
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C'mon guys, if you like my explanation, then gimme some kudos. I need the CLUB tests for a lot of practise.
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New post 01 Dec 2009, 07:56
BarneyStinson wrote:
C'mon guys, if you like my explanation, then gimme some kudos. I need the CLUB tests for a lot of practise.


LOL! What is kudos? I'm never heard of that before. And how can I give it to you anyways?
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New post 07 Nov 2011, 12:35
GMATFIGHTER wrote:
bsv180985 wrote:
BTW, i see you initially opt A as an answer?)) What makes you change decision?

GMATFIGHTER wrote:
For the first question, I pick A as my answer. I chose A because it implies that the screening test could be made to disqualify people carrying different diseases other than NANB hepatitis. Option A says "other infections for which reliable screening tests are routinely performed." If that's the case, then it makes sense why the screening test can miss 2/3 of the people carrying the NANB hepatitis.


Yes you're right, I initially chose A as my answer because I missed "reliable screening test." But after noticing that thanks to BarneyStinson, I corrected myself and rather agree that option E should be the answer.



Hi,

I think E would imply that the screening is 100% invalid, because only then, the frequency of all donors can be matched with the donors of having NANB. This would not support the conclusion and hence is not an assumption.

A, on the other hand, though seems a little off topic, when negated, will certainly shake the conclusion and thus acts as an underlying assumption. Therefore, POE,and just in comparison, the ans would have no other choice rather than A. OA's?????
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New post 23 Dec 2011, 05:21
IMO A for the first question and D for the second question. Any chance of getting the OAs?
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New post 22 Jun 2016, 12:08
The OAs are A & D.

As for the first question it is a tricky one.

This is my explanation from my CR log:
Ok this one is tricky, first IT IS AN ASSUMPTION, second we have to READ CLOSELY, we are told that the new test will disqualify 5% of donors, and so about 10% will still supply blood, this assumes that they are not eliminated in some other fashion, eg. they had other illnesses and had been eliminated, in this way the number would be lower than 10%.

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New post 14 Jan 2019, 06:25
apramanik wrote:
Questions 19-20 are based on the following.

Blood banks will shortly start to screen all donors for NANB hepatitis. Although the new screening tests are estimated to disqualify up to 5 percent of all prospective blood donors, they will still miss two-thirds of donors carrying NANB hepatitis. Therefore, about 10 percent of actual donors will still supply NANB-contaminated blood.

19. The argument above depends on which of the following assumptions?

(A) Donors carrying NANB hepatitis do not, in a large percentage of cases, carry other infections for which reliable screening tests are routinely performed.
(B) Donors carrying NANB hepatitis do not, in a large percentage of cases, develop the disease themselves at any point.
(C) The estimate of the number of donors who would be disqualified by tests for NANB hepatitis is an underestimate.
(D) The incidence of NANB hepatitis is lower among the potential blood donors than it is in the population at large.
(E) The donors who will still supply NANB-contaminated blood will donate blood at the average frequency for all donors.

20. Which of the following inferences about the consequences of instituting the new tests is best supported by the passage above?

(A) The incidence of new cases of NANB hepatitis is likely to go up by 10 percent.
(B) Donations made by patients specifically for their own use are likely to become less frequent.
(C) The demand for blood from blood banks is likely to fluctuate more strongly.
(D) The blood supplies available from blood banks are likely to go down.
(E) The number of prospective first-time donors is likely to go up by 5 percent.

Spoiler: :: OA
19's A, 20's D



OPEN DISCUSSION OF QUESTION #1 IS HERE: https://gmatclub.com/forum/blood-banks- ... 82406.html

OPEN DISCUSSION OF QUESTION #2 IS HERE: https://gmatclub.com/forum/blood-banks- ... fl=similar

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Re: Questions 19-20 are based on the following. Blood banks will   [#permalink] 14 Jan 2019, 06:25
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