IMO E

OA please.

i think its A.
if 100 potential donors are in contention, 5 are ruled out by NANB test.
the premise says that abt 2/3 rd of all NANB carriers are still not detected ( about 10 )
so if these 10 are still not detected and NANB carriers form 10% of the total actual donors ( considering actual donors = 100) then it means that these NANB carriers didn't have other infections which could be detected by other tests..

OA please.. can sm1 pls shed some light on this problem..

paes wrote:IMO E

OA please.

I too went for E. But that is not the OA

Can anyone explain wat is d assumption for this argument?

IMO C

pl. provide the OA....

IMO D.

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.

A:Donors carrying NANB hepatitis do not, in a large percentage of cases, carry other infections for which reliable screening tests are routinely performed. -> other infections is out of scope

B:Donors carrying NANB hepatitis do not, in a large percentage of cases, develop the disease themselves at any point. --> if the donor develops the disease or not, is irrelevant to the argument's conclusion to hold true. Neither does negation weaken the argument

C:The estimate of the number of donors who would be disqualified by tests for NANB hepatitis is an underestimate. -->negation of this does not weaken the argumnet

(D) The incidence of NANB hepatitis is lower among the potential blood donors than it is in the population at large. ->negation of this choice, weakens the argument

(E) The donors who will still supply NANB-contaminated blood will donate blood at the average frequency for all donors.-->frquency of donation is not our main agenda


What is the OA?

The OA for this problem is A.

Hi Adi,

Can you get me the reasoning on why OA is A.

I thought the assumption on which it depends up on- "The incidence of NANB hepatitis is lower among the potential blood donors than it is in the population at large". Since the conclusion states - 10percent of actual donors will still supply NANB-contaminated blood.

I chose A. Here was my reasoning:


Conclusion: Therefore, about 10 percent of actual donors will still supply NANB-contaminated blood.

Premise: 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.

(A) Donors carrying NANB hepatitis do not, in a large percentage of cases, carry other infections for which reliable screening tests are routinely performed.

I debated between this and E. I ultimately went with A because it focused on screening. We're arguing that our screening process will let in NANB-contaminated blood. We're assuming here that the other screenings for other diseases will not catch the NANB contimated blood. Say a donor has both Malaria and NANB. The screening for malaria might be more accurate than that for NANB, so while they may slip by the NANB screening they will probably not slip through the Malaria screening. In order for the argument to be true, we're assuming that the NANB donors will not have other infections.

(B) Donors carrying NANB hepatitis do not, in a large percentage of cases, develop the disease themselves at any point.

This was outside of the scope so eliminated it.

(C) The estimate of the number of donors who would be disqualified by tests for NANB hepatitis is an underestimate.

The underestimation in the premise was of all contaminated blood. Now just blood contaminated with NANB. So I eliminated this one. This also doesn't make or break the conclusion.

(D) The incidence of NANB hepatitis is lower among the potential blood donors than it is in the population at large.

Outside of scope. We're not really talking about what happens with blood donors vs. non blood donors. This is about screening contaminated blood. Eliminated.

(E) The donors who will still supply NANB-contaminated blood will donate blood at the average frequency for all donors.

This was tempting and I actually was choosing between A and E. I reasoned that we're basing this argument on donors with NANB blood to be donating at the same rate as other donors.

This quesiton is from retired tests and should be studied carefully. We should ask Stacey for this

I consider A is special kind. Negation of A is a weakener and we think that A is an Assumption. But it is wrong, A is not in context of evidence

I label A "affect conclusion but not in context of evidence" I see this kind of answer choice many times in OG. This is tricky choice.

IMO E, negation of E is an weakener in context of evidence. If frequency of deseased persons increases, 10 percent may be disqualified and 20 percent can be missed.

Anyway, I think we should ask Stacey for this.