Because visual inspection cannot reliably distinguish certain skin dis

Hi,

Why not A is the answer?
I was confused between A and C.

A. Whether the visits of patients who require diagnosis of skin discolorations tend to be shorter in duration at the clinic than at the hospital

Whether the diagnosis is shorter in time in clinic and hospital is out of scope. The decision of the clinic to buy the machine or not depends on whether it will reduce costs (cost effective). Regardless of whether visits of patients at the clinic is shorter or longer than that at the hospital, it can still be cost effective (or not) to use the machine for diagnosis.

D. Whether in certain cases of skin discoloration, visual inspection is sufficient to make a diagnosis of skin cancer

Some may think that well if it is not reliable then it does not make sense to buy it. I see where they are coming from. At the first glance, I am not sure whether the use of the machine is still considered a kind of visual inspection. But the paragraph already says "At Westville Hospital, dermatological diagnostic costs were reduced by the purchase of a new imaging machine that diagnoses skin cancer in such cases as reliably as the tissue tests do." So I will assume it is reliable. And D does not address whether it will reduce diagnostic costs.

C. Whether the machine at the clinic would get significantly less heavy use than the machine at the hospital does

The upfront cost of the machine is expensive as stated in the paragraph. Then whether it will be used frequently or not affects its payback period and therefore affects the costs of the diagnosis in early years of operation.

Please provide official explanation.

i narrowed down to both now A says about thw timming of the patients which is not mentioned in the passage so eleminate no still the other one talks about the effeciency directly gmat mostly tests from the passage expect for a weaken strengthen or similarly flawed reasoning questions

Edit: This post has been edited to remove a potentially erroneous remark on the source material.

Hello, everyone. I feel compelled to respond here because I see that no Expert has yet done so. How about we jump in?

This is an Evaluate type of question, in which we need to assess a plan through the logic of the passage. Keep sight of just what the passage lays out to avoid getting sidetracked.

Issue: a dermatological clinic in Westville is considering buying [a new imaging machine that diagnoses skin cancer]

Hopeful outcome: to reduce diagnostic costs

Drawback: the machine is expensive

Note that the hopeful outcome is supported by information in the passage: At Westville Hospital, dermatological diagnostic costs were reduced by the purchase of a new imaging machine that diagnoses skin cancer. It is just a matter of whether the same result would occur at the dermatological clinic. Now that we have the facts straight, we can look at the answer choices.

There is no definite connection between the duration of patient visits and the frequency with which the new machine would be used. Sure, it could be true that shorter visits at the clinic could lead to increased usage of the machine, but it could just as easily be true that the machine could only be used once per hour—the passage does not tell us how long the machine takes to reliably diagnose skin cancer—so the potentially quicker turnaround time of patients at the clinic would not make a difference.

If the machine works, as the passage tells us, then it works, plain and simple. This is not a relevant concern for the clinic.


If the machine at the hospital gets significantly more use, then the high cost of the machine might be justified, and the dermatological diagnostic costs might understandably have been reduced. If the machine at the clinic would, in fact, get significantly less heavy use, then the cost per use would be much greater, and it might not be in the best interest of the clinic to purchase the machine. Notice that the passage places the machine on level terms with tissue tests regarding the reliability of diagnoses. The machine is not better, so the clinic needs to find some economic reason to justify the purchase of the machine. This consideration, with its comparison, is pertinent to the matter at hand.

We already know from the first line of the passage that visual inspection cannot reliably distinguish certain skin discolorations from skin cancers (my italics), so it could be true that some cases of skin discoloration could be correctly diagnosed as skin cancer or as something else. Because of the lack of reliability in visually reading all cases of skin discoloration, the dermatologists at the clinics have needed to perform skin tissue tests. It is these tests that are being held in the balance against the purchase of the new machine, since, again, both the tissue tests and the machine are reliable in their diagnoses.

Whether these hospitals have or have not purchased imaging machines, the decision comes down to the anticipated financial benefit to the clinic. A greater or lesser number of hospitals with the machine will not affect the economic outlook.

In sum, only answer choice (C) can be justified. Watch those modifiers: significantly happens to be one of the most commonly used adverbs that GMAC™ likes to put in correct answers, since the appearance of such a word often makes the statement harder to argue against.

Good luck with your studies.

- Andrew

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