must be true ques

The evidence presented in the argument is not complete ,so we cannot infer anything something that is definitely going to happen ,because ,in that case,author will give another evidence that disproves your answer to counter the solution, the answer has to be something that is probable
(D) says vitamin C can help ,it doesn’t say it will help to prevent => correct

if you choose answer (C) ,to counter you answer author canl provide further evidence something like

Doses of vitamin C that exceed the standard recommended daily allowance by 600 percent will not reduce the incidence of serious cases of flu by 25 percent.


correct me if my explanation is wrong

I think it is D.

if all the groups were having balanced diets + vitamin C tablets when why is it wrong to assume that the balanced diet < 250mg? I assume the #s reported are the tablets+food. I dont get why E is wrong. Is it because it is not a hypothesis?
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Consider kudos, they are good for health

IMO D...
OA is also D. Mentioned at.... urch dot com / forums / gmat-critical-reasoning / 98722-nutritionist-studying-effects.html

I don't get how D can be the oa.
Massive doses of vit c is based on the 1500 case - fewer than 9 pc- but the premise does not specify how many serious cases were accounted for by these 9 pc. The 250 case and the no vit c other than balanced diet case mention atleast x serious cases. So let's say if these 2 cases only accounted for one serious case per ill person and the 9 pc case each ill person reports 2 mn serious cases where they fall I'll repeatedly - then though the number of 9 pc is less - the number of serious cases can be more and it could be that vit c massive dose has no effect. How does d satisfy the "must be true" test?

Posted from my mobile device

Quite a bit of confusion on this one... let's see if we can sort it out.

Read the question stem: Which of the following hypotheses is best supported by the evidence above?

The use of the word 'Hypotheses' signifies that what we are looking for is a proposition that is highly probable in the light of the data given in stimulus.
The stimulus provides evidence (premises) for one of the answer options. So that answer option must be a hypothesis that is supported by the stimulus.

Premises:
- massive doses of vitamin C found that of a 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;
- of a group of 600 people who took no vitamin C for a year (other than that found in the foods in a balanced diet), 32 percent suffered at least one serious case of flu.

Let's look at the options to see which one is supported by this data.

(A) The effectiveness of vitamin C in preventing serious cases of flu increases in direct proportion to the amount of vitamin C taken.
Not supported by the study. We do not know how much vitamin C was taken by people who took a balanced diet only. Anyway, we cannot establish the direct proportion.

(B) Vitamin C is helpful in preventing disease.
Too generic. Talks of disease in general. Not supported by the study.

(C) 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.
The popular but incorrect option. There is a difference between 'by 25%' and 'by 25 percent points'. If incidence of serious cases of flu was 34% and it reduces to 9%, that is a reduction of (34-9)/34 = 73.5% in the incidence. Or I can say that the incidence of serious flu has reduced by 25 percent points.
Similarly from 5%, if the growth rate goes up to 6%, that is an increase of 1/5 *100 = 20% (not 1%)
But I can say that the growth rate has increased by 1 percent point.

(D) Massive doses of vitamin C can help to prevent serious case of flu.
This is the hypothesis that is best supported by the study. Please note that it is not a 'must be true' statement. The author has already mentioned that these are hypotheses. We need to pick the one that is best supported by the stimulus. It is clear what massive doses are since the premise mentions "studying the effects of massive doses of vitamin C found that of a group...". The results of the study imply that massive doses of vitamin C can help prevent serious case of flu.

(E) A balanced diet contains less than 250 mg of vitamin C.
No information about this. If anything, in the group taking a balanced diet, the incidence of serious flu was slightly less than those taking 250 mg. So if we do want to infer something, we might be tempted to infer (wrongly, let me add) that a balanced diet has more than 250 mg of Vitamin C. We also don't know what kind of diet was taken by people taking 250 mg of Vitamin C.

Answer (D).
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According to the websters dictionary "hypothesis" can mean one of 3 things. One of the listed meanings is: an assumption

When the GMAT uses the word "hypothesis" does it require the use of the "must be true" test associated with an assumption or even a conclusion or a simple can be true/likely standard used for strengthen/weaken questions?

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Hypothesis means it is not an established fact. It is either used as 'working hypothesis' where it is a guess to guide further investigation or it is something highly probable in light of evidence provided. The second meaning is the way the word has been used here.

When the dictionary says that a hypothesis could be a mere assumption too, it means something that is not established to be true. Something that is just being assumed for some purpose. When we use 'assumption' in our CR questions as in 'which of the following is an assumption in the argument?', we mean that the argument was given by assuming something. [highlight]That assumption was taken to be true to arrive at the conclusion.[/highlight] That is why we check for 'must be true' with respect to the conclusion.

Conclusion is what you can infer without doubt. If the given premises are true, it must be true.
You can see a question that says "Which of the following can be concluded from the argument above?"
But you will not see "Which of the following hypothesis can be concluded from the argument above?" It will be "Which of the following hypothesis is [highlight]best supported[/highlight] by the argument above?"
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A nutritionist studying the effects of massive doses of vitamin C found that of a 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 of a group of 600 people who took no vitamin C for a year (other than that found in the foods in a balanced diet), 32 percent suffered at least one serious case of flu.

Which of the following hypotheses is best supported by the evidence above?

(A) The effectiveness of vitamin C in preventing serious cases of flu increases in direct proportion to the amount of vitamin C taken.
(B) Vitamin C is helpful in preventing disease.
(C) 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.
(D) Massive doses of vitamin C can help to prevent serious case of flu.
(E) A balanced diet contains less than 250 mg of vitamin C.