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Unit 1: Lesson 10

Reading Comprehension - Worked Examples

Inferences about info | Science passage | The Sun

Watch a demonstration of one way to answer an Inferences about information question from a science passage on the LSAT. Created by Dave Travis.

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Video transcript

- [Narrator] Which one of the following statements about spectroscopy is most strongly supported by the information in the passage? Okay, so this is strongly supported by the information in the passage, we can use the passage and look around for it, hopefully we have some idea about how spectroscopy was mentioned, it seemed like a pretty valid thing, that the data was misinterpreted, at one point, to think that iron was the major element in the sun, and then we know about spectroscopy, that Cecilia Payne reinterpreted that data to find that hydrogen and helium were the predominant elements in the sun. Okay, so let's look at these choices. It's use during the 1920s was generally confined to the field of astronomy. I'm not sure that was mentioned. We shouldn't leap to a conclusion about that. I'm not really liking that choice. It yielded data about the sun's composition that Payne initially doubted but ultimately came to accept. Well, it yielded data, well did she doubt the data? I'm interested in this choice a little bit, I may leave it in for now, but we don't really know that she initially doubted the data. She believes the data, she's a scientist, it's the interpretation of the data that we're kind of wondering about. So let's keep looking. It played a crucial, though often unacknowledged role in the emergence of our present day understanding of the process of nuclear fusion. We don't know if it's unacknowledged, that seems like a reach, I'm not really liking that choice, just because of this, we don't really hear about that in the passage, so I'm gonna move on. D, it was regarded by certain prominent scientists in the 1920s as an unproven tool that produced data of often questionable reliability. No, we don't really hear of any prominent scientists of the 20s doubting the data, calling it unproven, calling it questionable reliability, that is definitely not mentioned, D is out. E, it was a technique advanced enough by the 1920s to detect the presence in the sun of elements that constituted considerably less than 10 percent of it's mass. Okay, well maybe that's there, I kinda like that as well, I'm gonna go back to the passage in a second to look, because this is pretty specific. And if we learned ultimately that there are trace elements, then they knew that there were other things in there, let's look for that, that could be right. But let's also, we don't know this. Generally confined to the field of astronomy, I'm not really looking for evidence for A. And what we're also looking for is whether Payne actually initially doubted the data about the sun's composition. She doubted the interpretation of that data, but whether she doubted the data, that connection makes me really not like B. Okay, so we're going back up, and we're gonna look for whether or not spectroscopy was able to detect the presence of things that were kind of trace elements in the sun. Okay, so let's head up and see what we can find. We have a percentage here, that number kind of points us in the right direction, let's see whether we can find something we need here. Okay, She analyzed without preconceptions, she found the data could be consistently read as indicating that while it does indeed contain iron, along with other elements found on Earth, 90 percent of the sun is hydrogen, and most of the remainder is helium. Okay so, if 90 percent we now know is hydrogen, and most of the remainder is helium, and if the data tells us that it does indeed contain iron, okay, that means that this iron must be less than 10 percent. Okay, so that's pointing us in the right direction to how to answer this question. Let's go back. It was a technique advanced enough by the 1920s to detect the presence in the sun of elements that constituted considerably less, okay so they detected iron, and iron turned out not to be even 10 percent of the mass of the sun. This is definitely our answer.