Got a PM asking me to reply to this question:
goyalsau wrote:Q.5 -
A nutritionist studying the efforts of massive doses of vitamin C found that of group of 600 people who regularly took 1,500 mg of vitamin C daily for a year, fewer than 9 percent suffered serious cases of flu; of a group of 600 people who took 250 mg of vitamin C (the standard recommended daily allowance) daily for a year, 34 percent suffered at least one serious case of flu; and group of 600 people who took no vitamin C for a year ( other than found in the food in a balanced diet ), 32 percent suffered at least one serious case of flu.
Which of the following hypothesis is best supported by the evidence above?
a) Doses of vitamin C that exceed the standard recommended daily allowance by 500 percent will reduce the incidence of serious cases of flu by 25 percent.
b) Massive doses of vitamin C can help to prevent serious case of flu.
c) A balanced diet contains less than 250 mg of vitamin C.
d) The effectiveness of vitamin C in preventing serious cases of flu increases in direct proportion of the amount of vitamin C taken.
e) Vitamin C is helpful in preventing diseases.
Even though this question asks for the "hypothesis that is best supported" this is really another way to ask for the inference. So the best way to do this type of problem is to eliminate those answer choices that "could be false."
For this particular problem, a good idea would be to understand the type of language that is likely to be too strong for inference questions. On an inference question an answer choice that claims that something "will happen" or is "always true" requires a very high level of proof; such statements basically need to have already been made in the stimulus. In this case we have only one experiment with some results. It will be nearly impossible to come up with an absolute statement, such as "is true."
For example, if the experiments above showed that every person who took enough vitamin C was then able to fly in air like a bird, we could not say that "vitamin C causes you to be able to fly" or that "if you take vitamin C you will be able to fly." These things have not been proven. All that we can say is either "some people who took vitamin C were also able to fly" or "it is possible that taking vitamin C may be linked to flying." Notice how the possible answers are not absolutes but only state possibilities.
I often give this example in class that plays off of the fact that at Veritas nearly 1/3 of all of our students score over 700 on the actual GMAT. I say to the students, "which of the following will be easier to prove, If I say, "Each of you will score over 700 on the GMAT within the next 3 months," or "Many of you may do well on the GMAT"? The first statement is the one that everyone wants - but in a class of 10 - 15 students that would be very difficult to prove. Whereas the second statement is very easy to prove. "Many" could really mean any number more than one or two, and the word "may" simply indicates the possibility rather than the certainty.
In this case of this particular problem, Answer Choice B is the only one that is even possible to conclude given the very limited evidence of just one study - a study that makes no broad claims but only reports a few facts.
Answer choice A claims that taking very large doses of vitamin C "will reduce the incidence of serious cases of flu by 25 percent." This answer has two flaws, it is too definite for the stimulus and it is too specific in saying 25%.
Answer Choice C would go beyond the stimulus. We know the recommended daily allowance of vitamin C, but does a balanced diet meet this requirement? We do not know.
Answer Choice D is far too definite and specific. It states, "The effectiveness of vitamin C in preventing serious cases of flu increases in direct proportion of the amount of vitamin C taken." Really, so if I took 1 million mg of vitamin C this would be even more effective? It would also be fatal. We only know that some people who took a high dosage of vitamin C had fewer incidences of the flu in this particular study. And, as mentioned above, those who take a little bit of Vitamin C actually had more cases of flu than those who took none, so we can say that D is not accurate.
Answer Choice E is something that is true in the real world. Vitamin C is useful at preventing certain diseases, ask the British Navy where they started carrying lime juice on their ships in the 1700s. However, the stimulus does not reference "diseases" only the flu.
Answer Choice B is the best choice, "Massive doses of vitamin C can help to prevent serious case of flu." If you interpret the "can" as "may possibly" then you see this is just saying that it is possible. Well not only is "anything possible" but we have some evidence in the stimulus that might lead us in this direction.
Hope that helps!
