Many of today’s mathematicians use computers to test cases that are ei

Question

Many of today’s mathematicians use computers to test cases that  are either too time-consuming or involve too many variables to test manually, allowing the exploration of  theoretical issues that were impossible to test a generation ago

(A) are either too time-consuming or involve too many variables to test manually, allowing the exploration of

(B) either take too much time or involve too many variables to be tested manually; allowing the mathematicians to explore

(C) would either take too much time or involve too many variables to test manually, allowing them to explore

(D) would either be too time-consuming or would involve too many variables to test manually; this capability allows the mathematicians to explore

(E) take too much time or variables to test manually; this capability allows the mathematicians to explore

sivasanjeev · Accepted Answer

Many of today’s mathematicians use computers to test cases that  are either too time-consuming or involve too many variables to test manually, allowing the exploration of  theoretical issues that were impossible to test a generation ago

a) are either too time-consuming or involve too many variables to test manually, allowing the exploration of 
Either ... or construction is a parallel marker. 'Or' is followed by a verb and hence, 'either' too should. Because the helping verb 'are' is used before either, this option is wrong.

At an advanced level, 'exploration of' usage is wrong too. Because, participle 'allowing' is modifying the entire clause and we don't know who is doing the 'exploration'. A preferred construction would be 'allowing X to explore ....'. Verb form is preferred over noun form.

b) either take too much time or involve too many variables to be tested manually; allowing the mathematicians to explore 
The part of the sentence after the 'semicolon' is not a clause. Eliminate B.

c) would either take too much time or involve too many variables to test manually, allowing them to explore 
Errors mentioned in A are corrected here.

d) would either be too time-consuming or would involve too many variables to test manually; this capability allows the mathematicians to explore 
'or' is followed by 'would' and so should 'either' be.
Also, 'this' doesn't have a clear referent. Ask yourself, 'this capability' means 'which capability' ??

e) take too much time or variables to test manually; this capability allows the mathematicians to explore 
'or' is the parallel marker - 'take too much' and 'variables to test' are not parallel. 'this' doesn't have a clear referent.

GMATNinja · Answer

When you see a verb-ing modifier after a clause, the most important thing is to figure out whether that modifier logically describes the preceding clause. There's a pervasive myth that the verb-ing modifier should logically describe the previous subject, and this kind of narrow analysis can get you into a little bit of trouble. Take a silly example. "The neighbor's dog bit Natalie's pinkie toe, prompting her husband to call an ambulance." This is perfectly fine. (Although let's all agree that Natalie's husband is overreacting here, and this dog has weirdly precise aim.

) Did the neighbor's dog prompt Natalie's husband to call an ambulance? Not exactly. This isn't Lassie magically telling someone to call for help. But it is 100% true that the fact that the dog bit Natalie -- in other words, the dog's act of biting Natalie -- prompted her husband to make the phone call. In other words, "prompting" logically modifies the preceding clause, even though it doesn't logically modify that clause's subject in isolation . The same thing is true of the question in this thread. "Mathematicians" is the subject of the first clause. Do mathematicians allow the exploration of difficult theoretical issues? Not exactly. But does the fact that "mathematicians use computers to test tough cases" allow the exploration of difficult theoretical issues? You bet it does. So the "verb-ing" usage is just fine here, even though it doesn't modify ONLY the subject. I hope that helps!

djanand · Answer

Is the usage of pronoun "them" correct ? As per my understanding,keyword  them  can have two antecedents namely, today’s mathematicians and computers. Though today’s mathematicians is the subject of the sentence, how can we be sure that the pronoun  them  is referring to the subject and not to  computers ? Is it the case that the exploration work can be done by  today’s mathematicians , hence the keyword  them   must refer to mathematicians (not to computers) ?

Rock750 · Answer

Well, Pronoun ambiguity is not an absolute rule upon u can eliminate with confidence an answer choice. In the answer choice C, them logically refers to today's mathemiticans who are able to explore something not the computers. If another answer choice has not any grammatical error, conveys the meaning and clears the doubt about the prounoun ambiguity then it would win over C but in absence of that choice, you should go for C and move on.

PiyushK · Answer

Between C and E.

E. take too much time or variables to test manually; this capability allows the mathematicians to explore

Too much time or variables -- variables are countable noun thus we can not put it in parallel with much.
Too much time or Too much variables (Incorrect)

IMO: no other option is better than C.

kinjiGC · Answer

Many of today’s mathematicians use computers to test cases that are either too time-consuming or involve too many variables to test manually, allowing the exploration of theoretical issues that were impossible to test a generation ago

a) are either too time-consuming or involve too many variables to test manually, allowing the exploration of
 There is a parallelism issue
Many of today’s mathematicians use computers to test cases are too time-consuming
Many of today’s mathematicians use computers to test cases are involve too many variables to test manually
We need to repeat "are" in both the lines and then you can see the issue - Incorrect

b) either take too much time or involve too many variables to be tested manually; allowing the mathematicians to explore
 Allowing is a verbing modifier to join the two clauses and cannot be separated by a semi colon. Either side of Semi colon shouldn't dependent on each other "Structurally" bur should depend on meaning wise. - Incorrect

c) would either take too much time or involve too many variables to test manually, allowing them to explore
 Perfect

d) would either be too time-consuming or would involve too many variables to test manually; this capability allows the mathematicians to explore -  Extra would

e) take too much time or  variables to test manually ; this capability allows the mathematicians to explore -  Doesn't make sense to me at all

Aves · Answer

I have a question.

1) Which noun is the subject of the action 'allow'? cases or mathematicians?

Both of them don't make sense in my opinion. It should be the computers.

And the modifier will be like this

"the computers allow today's mathematicians to explore theoretical issues that were impossible to test a generation ago."

Am I right?

chetan2u · Answer

Hi,

allowing is the VERB +ING modifier and does not modify ant particlar NOUN.
It modifies the preceding clause..

here it is talking of the result of previous clause --Many of today’s mathematicians use computers to test cases

Aves · Answer

Hi chetan2u,

I know that V-ing modifier modifies the preceding clause as a whole but it should make sense with the subject of the preceding clause as well, shoudn't it?

PrakharGMAT · Answer

HI GMATify , I opted for correct option C but I would like to discuss the usage of "WOULD". I eliminated other options and in the end left with option C. But other approach would have been we directly eliminate options A,B and E as "Would" is not used. I hope in this sentence condition is required so "Would" is required...Please correct me if I am wrong. Can we do this.. :?:

Please assist.

dina98 · Answer

Could someone please explain/validate the usage of "this" in independent clauses following a semi-colon? I've seen examples where "this" is ok.. confused. Are such examples wrong?

tarunk31 · Answer

this, that, these, and those can act as demonstrative adjectives or demonstrative pronoun.They are called demonstrative as they indicate the location of something.

On GMAT, the use of demonstrative adjectives is fine. For example.

This pen is mine and that one is yours.

Notice that in this sentence this and that are adjectives of nouns pen and one respectively.

The following use of demonstrative pronouns is almost always wrong on GMAT:

This is my pen. 
That is good shot. 
 
Here  this  and  that  are subject pronouns. Here, this and that are too ambiguous. You can not really relate to the location of the object/thing unless you are actually looking at it.

Demonstrative pronouns when used to indicate the copy of nouns in comparisons is also correct on GMAT. For example:

The population of India is greater than that of US.
 
Here  that  refers to population.

GMATNinja · Answer

Responding (very belatedly) to a PM: I think the "rule" you're referring to is this one: a non-possessive pronoun can't generally refer to a possessive noun on the GMAT. (An astute forum member pointed out an exception to this rule on an official question: https://gmatclub.com/forum/sc-og-208881.html. But it's the only one I've ever seen... so I suppose that we can demote this from a "rule" to "a guideline that usually seems to work." Ugh.) But even if we're trying to enforce the original "rule", there's no problem with the pronoun here at all. "Them" refers back to "mathematicians", which isn't actually possessive. So you're all good here. I hope this helps!

pikolo2510 · Answer

Hey  GMATNinja  ,  GMATNinjaTwo  ,  adkikani  ,  abhimahna

Although I got this right, I'm confused with the usage of 'verb-ing' at the end of the sentence. Allow me to explain

verb-ing when preceded by a comma can only do two things
1. Presents additional information for the preceding clause
2. Tells the result of the preceding clause
Note: - The verbing should make sense with the subject of the preceding clause

In the given question, the preceding clause is

With the above information, the noun in the preceding clause 'test cases' doesn't make sense with the verbing 'allowing'. Test cases cannot do the work of 'allow'

Can you let me know where am I going wrong?

Harsh2111s · Answer

GMATNinja   MentorTutoring

Explanation of Questions i have encountered till now force me to not to change the intended meaning of the sentence.
But here in option C, use of "would" changes the meaning of original sentence.

Kindly explain the above paradox.
Are these situations can appear in official questions also ?

AndrewN · Answer

Hello,  Harsh2111s . There is a myth that surrounds the original sentence, namely that it is the one that displays the intended meaning, that all the other answer choices must reflect it. If such were the case, then there would be a lot more correct (A) answers, I can assure you. The only parts of the original sentence that you cannot negotiate are those in the  non-underlined  portion. In the sentence at hand, it could be the case that the sentence could adopt either the present or present conditional forms. There are issues, however, that prevent us from choosing any of the answers that adopt the present-tense versions in (A), (B), or (E), as others have noted above, even if (B), in my mind, comes close. One could argue that the sentence is intending to say that mathematicians are  not  downing time on these  cases , so the conditional tense is necessary. But I would say that the use of  many  at the head of the sentence precludes such a definitive argument. If many, but not all, mathematicians use computers to test certain cases, then the process may very well be too time-consuming for those who are doing it the old-fashioned way, and it could be this group of mathematicians the sentence was referring to, by way of comparison.

- Andrew

gvij2017 · Answer

Here I have a reservation about use of Ving modifier.

Case-1 
V+ing ......, clause. 
Here V+ing modifier will modify the subject only. 
Ex. Pointing his finger towards moon, He said that one day he would be there as an astronaut.

Case-2
Clause, V+ing..... 
Here V+ing modifier modifies the preceding clause. 
As in given problem.

Is my understanding correct?

chetan2u · Answer

Yes, you are correct. Add to it that without comma the verb+ing modifier modifiers preceding noun.

Thelionking1234 · Answer

Official Explanation

According to this sentence, many of today’s mathematicians use computerized testing for two kinds of cases: first, those that take too much time for manual testing, and, second, those containing too many variables for manual testing. The structure used to introduce these cases, either X or Y, demands parallelism.
 
(A) Too time-consuming and involve too many variables are not parallel. Because the verb are appears before the parallelism marker either, parallelism dictates the following reading of the second item: to test cases that are involve too many variables. The second item has two verbs!
 
(B) A semi-colon (;) is used to connect two complete sentences. In this choice, the second portion (allowing…) is not a complete sentence.
 
 (C) CORRECT. Take too much time and involve too many variables are properly parallel. The change to the hypothetical form would is acceptable because the sentence indicates that these cases would not be tested if they had to be tested manually. The pronoun them is also acceptable, as it points back to the subject of the first half of the sentence (many of today's mathematicians use computers, allowing them to explore...). 
 
(D) Be too time-consuming and would involve too many variables are not parallel. Because the verb would appears before the parallelism marker either, parallelism dictates the following reading of the second item: to test cases that would would involve too many variables. The second item repeats the word would!
 
(E) The word variables is a countable noun, so it needs to be modified by the adjective many, not the adjective much (which is used for uncountable nouns). This choice may seem more concise than others, but it introduces a modifier error.

Many of today’s mathematicians use computers to test cases that are ei

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Many of today’s mathematicians use computers to test cases that are ei

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

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