BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Target Test Prep · GMAT

Choose how you want to prepare

Learn live with an expert or move at your own pace. Every option includes the complete TTP study system.

★★★★★5.0559 reviews
GMATLiveTeach 7 seats left
Chris Peckover
NEXT LIVE COHORT

Oct 13 to Jan 7, 2027

with Chris Peckover

Schedule
Tue, Thu · 8:00 to 10:00 PM ET
Included
40 live hours + 6 months of GMAT OnDemand
  • Live instruction and real-time questions
  • Class recordings and assigned practice
View class & enroll
Limited cohort · enrollment openTarget Test Prep
EALiveTeach 5 seats left
Logan Thompson
EXECUTIVE ASSESSMENT

Sep 6 to Dec 6, 2026

with Logan Thompson

Schedule
Sun · 9:30 AM to 12:30 PM ET
Included
Live EA class + 6 months of EA OnDemand
  • Expert-led weekly online sessions
  • EA Masterclass access between classes
View EA class & enroll
Limited cohort · enrollment openTarget Test Prep
GMATOnDemand Start anytime
SELF-PACED MASTERCLASS

Target Test Prep GMAT OnDemand

Complete access from day one. Study on your schedule.

130-point score guarantee
$0to start then $127/mo
  • Personalized study plan and analytics
  • Thousands of lessons and practice questions
Start free 5-day trial
Read 559 reviewsTarget Test Prep

Compare the format, schedule, and included access before enrolling. Prices and seat counts shown reflect the supplied offer details.

SC - GMAT Prep

Expert replies
Post new topic Locked
Previous Topic Next Topic
Source: — Sentence Correction |
User avatar
Master | Next Rank: 500 Posts
Posts: 410
Joined: Fri Mar 13, 2015 3:36 amFollowed by: 8 members
Location: Worldwide
Thanked: 120 times
GMAT Score:770

by OptimusPrep » Thu Jun 30, 2016 11:07 am
girishj wrote:Why is B correct and E wrong?
The westinghouse air brake, first demonstrated successfully in 1868, had been developed to such an extent by 1887 that a train of 50 freight cars traveling at 20 miles per hour could be brought to a standstill in the space of 171 feet, whereas before they required 5 hand breakers over a distance of 1,500 feet for such a train to be stopped.

(a) whereas before they required 5 hand breakers over a distance of 1,500 feet for such a train to be stopped.
(b) whereas previously 5 hand breakers operating over a distance of 1,500 feet had been required to stop such a train.
(c) but before stopping the train required 5 hand breakers operating over a distance of 1,500 feet.
(d) but previously they required 5 hand breakers over a distance of 1,500 feet stopping the train.
(e) but before stopping such a train required 5 hand breakers over a distance of 1,500 feet.
We need to understand the meaning of the sentence before we start to solve.
There is a contrast here and "whereas" does that.

Moreover, in option E, before does not properly point to a time frame and this statement is just bad ...

Correct Option: B
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Junior | Next Rank: 30 Posts
Posts: 23
Joined: Tue Jun 28, 2016 6:39 amFollowed by: 3 members
Thanked: 8 times
GMAT Score:780

by Danny@GMATAcademy » Sat Jul 02, 2016 12:47 pm
The meaning in answer choice E veers slightly from the intended meaning of the original sentence.

The original sentence indicates that, in the past, hand brakers were used to stop the train.

Answer E suggests that the hand brakers were just a thing trains needed prior to stopping.

This is related to the time-frame issues. The before in E seems to be modifying the gerund stopping. So the second half of the sentence (what follows the comma-but) has a structure similar to 'before speaking you need to think.' 'before stopping trains need these braker things' does not give the 'in the past' idea from the original.

B makes clear that the hand brakers were used to stop the train ('hand breakers operating...') and it is clear that we are talking about an earlier time-frame (previously doesn't have the ambiguity problems of before, because previously cannot be used as a preposition).
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
GMAT Instructor
Posts: 15539
Joined: Tue May 25, 2010 12:04 pmFollowed by: 1906 members
Location: New York, NY
Thanked: 13060 times
GMAT Score:790

by GMATGuruNY » Wed Jul 06, 2016 2:39 am
Only SIMILAR THINGS can be compared.

E: The Westinghouse air brake had been developed by 1887, but before stopping such a train required 5 hand breakers.
Here, but serves to connect the two colored clauses above.
The subject of the red clause is not crystal clear.
It is possible that the subject of required is stopping, implying that the act of STOPPING SUCH A TRAIN required 5 hand breakers.
It is possible that the subject of required is such a train, implying that SUCH A TRAIN required 5 hand breakers before stopping.
Neither subject is similar to the subject of the blue clause (the Westinghouse air brake).
The result is an illogical comparison.
Eliminate E.

OA: The Westinghouse air brake had been developed by 1887, whereas previously 5 hand breakers had been required.
Here, the two subjects in blue are SIMILAR:
Each refers to a MECHANISM used to stop a train.
The result is a logical comparison.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.

As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.

For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Senior | Next Rank: 100 Posts
Posts: 64
Joined: Tue May 22, 2012 10:44 pm
Thanked: 1 times

by evs.teja » Wed Jul 06, 2016 5:57 am
Danny@GMATAcademy wrote:The meaning in answer choice E veers slightly from the intended meaning of the original sentence.

The original sentence indicates that, in the past, hand brakers were used to stop the train.

Answer E suggests that the hand brakers were just a thing trains needed prior to stopping.

This is related to the time-frame issues. The before in E seems to be modifying the gerund stopping. So the second half of the sentence (what follows the comma-but) has a structure similar to 'before speaking you need to think.' 'before stopping trains need these braker things' does not give the 'in the past' idea from the original.

B makes clear that the hand brakers were used to stop the train ('hand breakers operating...') it is clear that we are talking about an earlier time-frame (previously doesn't have the ambiguity problems of before, because previously cannot be used as a preposition).
Danny Sir,
I am having a hard time understanding what the sentence seems to imply.

The 1500 feetmentioned in the sentence implies which of the following.
1) The 5 hand brakes are spread over a distance of 1500 feet
2) OR With the help of these 5 hand brakes the train comes to a halt in 1500 feet.

Which of the above is the correct meaning ?
Kindly clear this doubt of mine.
Regards
Teja
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Master | Next Rank: 500 Posts
Posts: 199
Joined: Sat Apr 26, 2014 10:53 amFollowed by: 4 members
Thanked: 16 times
GMAT Score:780

by 800_or_bust » Wed Jul 06, 2016 5:59 am
girishj wrote:Why is B correct and E wrong?
Image
Choice (E) is a trainwreck. Pun intended. More seriously, the meaning is ambiguous as some of the others pointed out.
800 or bust!
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Junior | Next Rank: 30 Posts
Posts: 23
Joined: Tue Jun 28, 2016 6:39 amFollowed by: 3 members
Thanked: 8 times
GMAT Score:780

by Danny@GMATAcademy » Wed Jul 06, 2016 8:07 am
Danny Sir,
I am having a hard time understanding what the sentence seems to imply.

The 1500 feetmentioned in the sentence implies which of the following.
1) The 5 hand brakes are spread over a distance of 1500 feet
2) OR With the help of these 5 hand brakes the train comes to a halt in 1500 feet.

Which of the above is the correct meaning ?
Kindly clear this doubt of mine.
Regards
Teja
Hi Teja,

The ambiguity you point out is one of the reasons A, D and E are not good answer choices. In each of these, we can't tell whether the brakers are operated over a distance of 1500 feet or are spread out over a distance of 1500 feet. It's a good sign that you recognize this subtlte ambiguity.

Answer B makes it clear that the 5 brakers are operating over 1500 feet in order to stop the train. This matches your second option; the train stopped in 1500 feet. And this idea logically completes the comparison with the first half of the sentence (which states that later on airbrakes could bring this type of train to a stop in only 171 feet).

While we're talkng about ambiguity, note as well that A and D contain ambiguous pronouns. There is no clear antecedent for they.

Hope this helps,

Danny
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Junior | Next Rank: 30 Posts
Posts: 11
Joined: Sun Feb 09, 2020 9:16 am

Re: SC - GMAT Prep

by yxfmoon » Sun Feb 09, 2020 2:30 pm
Can before be an adv. like previously so the subject of option C and E is stopping the train?
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Senior | Next Rank: 100 Posts
Posts: 38
Joined: Thu Dec 17, 2015 9:22 am

Re:

by gui_guimaraes » Wed Jul 29, 2020 9:31 am
GMATGuruNY wrote: ↑
Wed Jul 06, 2016 2:39 am
 Only SIMILAR THINGS can be compared.

E: The Westinghouse air brake had been developed by 1887, but before stopping such a train required 5 hand breakers.
Here, but serves to connect the two colored clauses above.
The subject of the red clause is not crystal clear.
It is possible that the subject of required is stopping, implying that the act of STOPPING SUCH A TRAIN required 5 hand breakers.
It is possible that the subject of required is such a train, implying that SUCH A TRAIN required 5 hand breakers before stopping.
Neither subject is similar to the subject of the blue clause (the Westinghouse air brake).
The result is an illogical comparison.
Eliminate E.

OA: The Westinghouse air brake had been developed by 1887, whereas previously 5 hand breakers had been required.
Here, the two subjects in blue are SIMILAR:
Each refers to a MECHANISM used to stop a train.
The result is a logical comparison.
Hi @GMATGuruNY Isn't it "stoping" on C and E a dangling modifier? tks!
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Locked
• Page 1 of 1