LR Question 6 Explanation
QUESTION TEXT: While grapefruit juice is a healthy drink, it has…
QUESTION TYPE: Weaken
CONCLUSION: We should take lower doses of medicines combined with grapefruit juice.
REASONING: A chemical in grapefruit juice increases the effect of medicines. It’s always best to take the smallest dose of medicine that will produce the desired effect.
ANALYSIS: Medical doses need to be precise. This argument tells us that grapefruit juice increases the effect of medicine. It doesn’t tell us how much the effect is increased, or if it’s constant for all medicines or for all quantities of grapefruit juice.
We have two options:
- Rigorously test the right amount of grapefruit juice for all medicines, and make sure that patients take exactly that quantity with the right amount of chemical.
- Tell patients to avoid grapefruit juice.
Hmm, which is simpler…..?
___________
- CORRECT. This destroys the argument. Medical doses require precision. If we can’t be sure of the quantity of the chemical, then it’s impossible to predict the effect of grapefruit juice on medicines.
- This supports the argument. It provides an additional reason for replacing medicine with grapefruit juice.
- This just confirms that the chemical has an effect. But this information is irrelevant to the argument. The author said that we should give patients grapefruit juice with the chemical in order to reduce the required amount of medicine.
- This is just a random fact about how the chemical works. It has no impact on the argument.
- This tells us that doctors were aware that grapefruit juice had an effect before they knew why it had an effect. That’s an interesting fact, but it has nothing to do with whether patients should follow the radical course of action outlined in the stimulus.
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Thanks for great explanation. But It would be great if you could clarify more for the answer choice (D).
One of the most frustrating thing on LSAT for me, is that sometimes (especially in weaken/strengthen Qs), answer choices are correct for certain reasons, but in other questions, similar line of reasoning does not apply.
In this question, for example, the answer choice (D) could be understood in this way :
Ok, it works by this way. But what if this process hinders with how the medicine affects our body?
When I first read the stimulus, I immediately thought that “Ok, but isn’t there any other side effects when taking medicine with grape fruits? what if, even though it acts like pumping the doses, results in other detrimental effects?” So I thought (D) might pose a possibility.
You might say that, it does not indicate that this mechanism will not necessarily have negative effect. However, I have seen some questions that even the implicit suggestion of ‘possibility’ in the answer choices makes it a weakener.
Thanks in advance
In this case, the issue is that you’re bringing in outside information to rule out an answer choice. Given that we don’t have any indication otherwise from the stimulus, it’s equally possible that the grapefruit juice’s inhibition of an enzyme could have positive or negative side-effects. You’re assuming that it will have negative side effects, which is going beyond the letter of the answer choice.
You can rule out Weaken answer choices on the basis of “possibility” in the sense that the answer choices bring up a possibility that would weaken the argument that is not addressed in the stimulus.
I understand the reason why A is correct.
However, I am not quite sure why C is incorrect.
The answer choice C state that the chemical that affects the absorption of the medicine can be removed from the grape juice.
The stimuli state that the BEST medical approach is to take the lower dosage and pair it with the prescribed amount of grape juice.
But isn’t that if we can remove that chemical altogether, the best medical approach is just to take that substance out without have to worry it? And if there is something better than the proposed way of the medical approach, then the conclusion in the stimuli is not the best medical approach. So the answer choice C can weaken the arguement.
Remember, the stimulus states it is always desirable to take the lowest effective dose of the medication. That’s why the ideal approach is to take lower doses of the medication along with prescribed amounts of grapefruit juice. If you took the chemical that gives grapefruit juice it’s medical effectiveness out, then you’d need to take higher doses of medication because the grapefruit juice wouldn’t make normal medicinal doses act like higher doses.
So, all (C) does is provide more evidence that the chemical is the thing that makes the grapefruit juice medicinally effective. That doesn’t weaken the argument.
where does the ‘precision’ come from?
The stimulus tells us that getting the wrong dosage (which includes dosages that are both too high and too low) is dangerous. So, the dose must be precisely what’s necessary for the patient.
(A) weakens our argument because it means that using grapefruit would result in imprecise dosing. If the amount of the chemical within each glass is “highly unpredictable”, it’d be very difficult to calibrate how much grapefruit should be taken with how much medication in order to get the right dose for the patient. So if (A) is true it would definitely call into question the idea that taking grapefruit with medication is the best medical approach.
yes, I guess it’s sth. needs to be inferred from the stimuli, nice to get a reply from you~