Best support for the claim question

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lj88: Junior | Next Rank: 30 Posts; Posts: 23; Joined: Sun Feb 10, 2013 3:16 pm

by lj88 » Tue Feb 12, 2013 3:49 pm

Hi,

This question is from Peterson's Master the GMAT:

During the past week, 120 RamTech Corporation employees have reported symptoms of a strain of food poisoning known as disporella, but only 8 of these employees have tested positive for the strain. A RamTech spokesperson claims that the apparent outbreak of disporella can be attributed to contaminated food served two weeks ago at the company's annual employee picnic.

Which of the following, if true, would best support the claim made by the RamTech spokesperson above?

(A) Disporella symptoms generally last only a few days.
(B) RamTech's cafeteria facilities provide lunch to RamTech employees during every workday.
(C) People with disporella do not generally test positive for disporella until at least one week after disporella symptoms begin to occur.
(D) People with disporella often do not exhibit disporella symptoms until more than a week after contracting disporella.
(E) A person can test positive for disporella without exhibiting symptoms of disporella.

Can you explain why the answer is D?

Thank you!

Source: Beat The GMAT — Critical Reasoning | Tue Feb 12, 2013 3:49 pm

Kasia@EconomistGMAT: GMAT Instructor; Posts: 646; Joined: Mon May 21, 2012 7:08 amFollowed by: 143 members; Thanked: 322 times

by Kasia@EconomistGMAT » Wed Feb 13, 2013 12:34 pm

A - incorrect, this answer actually weakens the conclusion because if symptoms lasted only a few days, then the picnic 2 weeks before could not have been their cause
B - incorrect, out of scope - the statement is too general and does not concern the argument
C - if people tested positive at least one week after symptoms began to occur, then more people should test positive and not only 8 of them. Therefore, answer C does not strengthen the argument
D - correct, the statement proves that the picnic could have been the cause of the illness because the symptoms started showing more than a week after the picnic
E - out of scope, the argument does not talk about employees who don't exhibit symptoms but test positive

Kasia
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nisagl750: Master | Next Rank: 500 Posts; Posts: 145; Joined: Tue Jan 31, 2012 6:50 amFollowed by: 2 members; Location: New Delhi; Thanked: 16 times; GMAT Score:760

by nisagl750 » Wed Feb 13, 2013 10:40 pm

Kasia@EconomistGMAT wrote: D - correct, the statement proves that the picnic could have been the cause of the illness because the symptoms started showing more than a week after the picnic

Hi Kasia,

Thanks for the explanation.
I understood why A,B,C, & E are not the right answers. This leaves us with D (which has to be the right answer) But I still can't figure out solid reasoning for it. Is it O.K. to eliminate 4 options on solid grounds and select the fifth option even if I am not sure why it is right?

GMAT/MBA Expert

ceilidh.erickson: GMAT Instructor; Posts: 2095; Joined: Tue Dec 04, 2012 3:22 pmFollowed by: 247 members; Thanked: 1443 times

by ceilidh.erickson » Thu Feb 14, 2013 8:34 am

I tend to think that this is just not a very good question. D tells us why the symptoms would start showing more than a week after the picnic, but does nothing to address the fact that only 8 people tested positive, or that more than a week = two weeks exactly. So, this isn't a particularly well-written problem/answer choice.

But to your question:

Is it O.K. to eliminate 4 options on solid grounds and select the fifth option even if I am not sure why it is right?

Well, yes. There are certainly times that my fellow instructors and I have told students "look, I agree that it's not a very good answer. But you have to pick one, so pick the least terrible one!" Because CR is more open to interpretation than, say, the quant section, the answers will not always be perfect. Here, we're looking for "best supports," not "100% completely perfectly supports."

Your goal should be to prove answer choices WRONG, not find the right one. If you're doing that well, you'll often find reasons to quibble with all 5! Then just ask yourself - which answer choices do I have the strongest arguments against? If you have more solid logical grounds to eliminate the other 4, pick the 5th one without worrying too much about the fact that it's not perfect.

Ceilidh Erickson
EdM in Mind, Brain, and Education
Harvard Graduate School of Education

lj88: Junior | Next Rank: 30 Posts; Posts: 23; Joined: Sun Feb 10, 2013 3:16 pm

by lj88 » Wed Feb 20, 2013 10:06 pm

Thank you to both Kasia@EconomistGMAT and ceilidh.erickson.

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