Analyzing a Tough GMATPrep Sentence Correction Problem
Yesterday we tried to crack a GMAT quant problem, so today we're looking for the correct answer to a GMAT verbal question. Its been a while since weve tackled any SC lets try one. This problem is from GMATPrep.
Set your timer for 1 minute 15 seconds and go for it!
An international team of astronomers working at telescopes in the Canary Islands and Spain has detected at least 18 huge gas spheres estimated to have 5 to 15 times the mass of Jupiter, the solar systems largest planet.(A) astronomers working at telescopes in the Canary Islands and Spain has detected at least 18 huge gas spheres estimated to have 5 to 15 times the mass of Jupiter
(B) astronomers working at telescopes in the Canary Islands and Spain has detected at least 18 huge gas spheres estimated to be 5 to 15 times Jupiters mass
(C) astronomers is working at telescopes in the Canary Islands and Spain, having detected at least 18 huge gas spheres that are estimated at 5 to 15 times the mass of Jupiter(D) astronomers, working at telescopes in the Canary Islands and Spain, and has detected at least 18 huge gas spheres estimated at 5 to 15 times the mass of Jupiter
(E) astronomers, working at telescopes in the Canary Islands and Spain, has detected at least 18 huge gas spheres they have estimated to be 5 to 15 times Jupiters mass
When I did this problem, I was really surprised by one aspect of it. Was there anything that surprised you?
When I read the original sentence, it didnt sound that great. I found the working at telescopes part awkward. I didnt eliminate answer A, though, because Ive been tricked before. Awkward isnt a good enough reason to eliminate. So I scanned the other four answer choices vertically at that rough location and I discovered that all five answers say working at telescopes! So much for my ear. I think it still sounds awkward, but it must be okay because all five answers have it.
Sigh. Okay, so I have to find something else. The next thing I zeroed in on was the distance between team of astronomers and has detected. Now, in the original sentence, thats fine the word team is singular and so is the verb has. But I figured theyd mess that up in a few answers, so Id be able to eliminate based on this mistake. Again, I scanned the four remaining answers and I was shocked that not a single answer offered a plural verb to match the singular subject. This is what really surprised me about the problem they set up a classic structure for testing us on subject-verb agreement but they didnt follow through! They succeeded in getting me to waste a little bit of time.
What next? This problem is on the harder side for one very good reason: I couldnt really find anything wrong with the original sentence. On most sentences, we find an error in the original and that provides us with a starting point. Ive tried two starting points now and they were both dead ends.
At this point, I might decide to look at one of the other answer choices for clues. I might also look at the connection between the underlined and non-underlined portions of the original sentence. Lets talk about both paths.
If I decide to look at the underlined vs. non-underlined parts, I might notice that the end of the sentence contains a comma and then a modifier (the solar systems largest planet). Can I tell what kind of modifier that is? Yes, its a noun modifier and I can even tell what should come before the comma: the name of the planet or some other noun that refers to the planet. In the original sentence, thats fine Jupiter is right before the comma and that is, indeed, the name of a planet. Now, Id check the other answers and notice that, in B and E, the end of the underline changes to Jupiters mass. We cant describe the mass as the largest planet. I can eliminate B and E.
If I decide instead to examine another answer choice, I might start with answer B. I compare A and B, looking for differences, and then try to determine what the differences mean. (You can start with any answer you want, but you want to compare to A, and its physically easiest to compare B to A because theyre right next to each other so have a good reason if you decide you want to start with something other than B.)
In comparing A to B, I find two differences, both at the end of the underline. In A, we have to have 5 to 15 times the mass of Jupiter and in B, we have to be 5 to 15 times Jupiters mass. The word right before the to have / to be portion is estimated. Idiomatically, we do want to have an infinitive verb right after the word estimated so those are both okay from that perspective. Whats the difference between saying mass of Jupiter and Jupiters mass? Not a lot if we ignore the rest of the sentence.
In fact, when I did this one myself, I followed this second path, and when I got to the split between mass of Jupiter and Jupiters mass, I started asking myself Oh, does this have to do with meaning? Whats the difference in meaning between to have 5 to 15 times the mass of something and to be 5 to 15 times somethings mass? That question is annoying its more of a judgment call then a strict rule. I glanced back up at the original sentence and thats when I noticed that extra bit at the end, not underlined. Bingo! Theres a hard rule here the modifier rule and its clearly being broken in answer B. (I then scanned down the other answers and eliminated E for the same reason.)
So now were down to A, C, and D. I could read these two in their entirety, but that would take a lot of time so first, Im going to check the places that I know have already been tested. Ive already noticed that C and D both say mass of Jupiter, so theyre okay on that issue. We also had a split between estimated to have and estimated to be. What do C and D do with that portion of the sentence?
Yes! C and D say estimated at! Thats an idiom error "at" is a preposition, not an infinitive verb. I can eliminate both C and D.
The correct answer is A.
If that last step hadnt worked, then I would have had pick either C or D and compare it to A. Thats fine itll just take a bit longer, so lets first try to reuse our previous work as much as possible. Finally, there are some other errors in the answers... but I'm going to give you a task. Tell me what you think the other errors are in the comments; I'll reply to confirm.
Key Takeaways for I dont see anything wrong with the original sentence SC problems:
(1) Dont eliminate A just based on awkwardness. If you think something sounds awkward, check whatever the issue is in the other answers first. You might discover that the awkward thing is in all of the answers (and, therefore, correct!).
(2) Dont forget to examine the non-underlined portions of the sentence. Those portions are correct, but they have to connect in a certain way with the underlined portions, so you can use those connections to eliminate answers.
(3) If necessary, pick one other answer to compare to the original (or answer A); use that comparison to uncover what issues are being tested, and then use that knowledge to examine specific parts of the remaining answer choices.
* GMATPrep questions courtesy of the Graduate Management Admissions Council. Usage of this question does not imply endorsement by GMAC.