A study found that most of the strokes diagnosed by doctors occurred in the left side of patients' brains. This sugge...

Skylar on September 28, 2019

@bb427 Happy to help! Let's take a look.

This is an argument completion question. It states that the majority of diagnosed strokes occur in the left side and seeks to explain why right-side strokes are more likely to go undiagnosed than left-side strokes are.

However, we do not necessarily know that right-side strokes are more likely to go undiagnosed just because the majority of diagnosed strokes are in the left side. This raises a question of proportionality. Perhaps left-side strokes occur significantly more than right-side strokes- which could hypothetically be very rare. In this case, strokes on both sides could be diagnosed at an equal rate for the amount that they occur, which would explain why left-side strokes are seen more. Therefore, in order to claim that right-side strokes are more likely to go undiagnosed, we must know that they occur at a rate equal to the occurrence of left-side strokes. This would make them proportional and allow for them to be compared. Answer choice (B) is correct because it says just this. (B) states "it is very likely that just as many strokes occur in the right side of the brain as in the left side."

Answer choice (D) reads "the symptoms of right-side strokes tend to be different than the symptoms of left-side strokes." This does not provide grounds for making the strokes on both sides proportional and therefore comparable. For example, right-side strokes could have different symptoms than left-side strokes and still occur much less frequently. In this case, left-side strokes would be diagnosed more often because they occur more often, but it would not necessarily follow that right-side strokes are more like to go undiagnosed, as they would also be less likely to occur in the first place.

Does this make sense? Please reach out with any additional questions!

Abigail-Okereke on February 27, 2022

Hi Skylar, the explanation under the correct answer choice says the question is a strengthen question. I believe its an argument completion as well. If it is I suggest fixing that error so other students don't get confused.