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

Redeem
TTP OnDemand GMAT Video Course
Featured Course

Target Test Prep GMAT OnDemand

Scott Woodbury-Stewart’s private virtual classroom — 400 hours of master-class video lessons for the GMAT Focus Edition.

  • 715+ score guarantee — highest in the industry (99th percentile)
  • 52 chapters · 1,500+ lessons · 4,000+ practice questions
  • 400 hours of video · 1,500+ instructor-led HD smartboard lessons
  • 300,000+ students accepted to Harvard, Stanford, Wharton, Booth & Sloan & more
  • 24/7 live support + weekly Zoom office hours with GMAT instructors
  • TTP AI Assist — 24/7 AI-powered virtual tutor for instant help
  • 1,200+ flashcards + AI-powered study assistant & daily calendar
  • OnDemand, LiveTeach & GMAT Bootcamp formats available
  • Also: GRE, SAT Math & Executive Assessment courses
  • MBA Admissions Consulting now available
  • 🏆 2025 EdTech Breakthrough Award: Test Prep Solution Provider of the Year
  • 200,000+ students served
  • 5-day free trial — $0 to start, no auto-billing, cancel anytime
★★★★★ 5.0 (559 reviews)
130-pt guarantee
$0 to start then $127/mo
Start Free 5-Day Trial Read 559 Reviews →

Rate/Work DS - Really bugging me!

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
User avatar
Senior | Next Rank: 100 Posts
Posts: 77
Joined: Fri Mar 11, 2011 8:55 am
Thanked: 12 times
by wayofjungle » Sat May 14, 2011 9:52 am
Is the number of seconds required to travel D feet at R feet per second greater than the number of seconds to travel T feet at F feet per second?

1. D is 30 greater than T
2. R is 30 greater than F

[spoiler]This is Q87 from OG12, OA is E, but I am convinced the answer is C. When both statements are combined the question becomes is (T+30)/(F+30) > T/F right? In that case the answer should be 'yes'. OG gives no explanation, so please enlighten me if you understand. Thanks[/spoiler]
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Data Sufficiency |
User avatar
Master | Next Rank: 500 Posts
Posts: 436
Joined: Tue Feb 08, 2011 3:07 amFollowed by: 6 members
Thanked: 72 times

by manpsingh87 » Sat May 14, 2011 10:03 am
wayofjungle wrote:Is the number of seconds required to travel D feet at R feet per second greater than the number of seconds to travel T feet at F feet per second?

1. D is 30 greater than T
2. R is 30 greater than F

[spoiler]This is Q87 from OG12, OA is E, but I am convinced the answer is C. When both statements are combined the question becomes is (T+30)/(F+30) > T/F right? In that case the answer should be 'yes'. OG gives no explanation, so please enlighten me if you understand. Thanks[/spoiler]
1) D=30+T; since we don't have information about R and F hence 1 alone is not sufficient to answer the question.

2) R=30+F; since we don't have information about D and T hence 2 alone is not sufficient to answer the question.

combining 1 and 2 we have;

D=30+T and R=30+F;

therefore time taken in traveling D feet= 30+T/30+F;
and time taken in traveling T feet = T/F;

if T=F=2; we have time taken in traveling D and T feet=1 seconds;
if T=4 and F=2; time taken in traveling D distance would be; 34/32=17/16~1.06; while T/F=4/2=2;

as different results are possible depending upon different values of T and F hence answer should be E
O Excellence... my search for you is on... you can be far.. but not beyond my reach!
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Legendary Member
Posts: 516
Joined: Fri Jul 31, 2009 3:22 pmFollowed by: 13 members
Thanked: 112 times

by smackmartine » Sat May 14, 2011 10:10 am
IMO E

R(S1) = D & T(S2) = F , where S1 and S2 are respective times(in sec)
Asked : S1-S2 is -ve or positive

1) D=T+30 , NO info about relation between Rates --> Insufficient
2) R=F+30 , NO info about relation between distance--> Insufficient

Combining 1 and 2

S1-S2 = (D/R) - (F/T) = (T+30)/R - (R-30)/T ----> There is no way we can solve this expression using two unknown variables , So Insufficient
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Senior | Next Rank: 100 Posts
Posts: 77
Joined: Fri Mar 11, 2011 8:55 am
Thanked: 12 times

by wayofjungle » Sat May 14, 2011 11:21 am
Yikes. I was stuck on the concept as discussed on page 28 of the 2nd MGMAT Guide (Fractions, Decimals...) which states:

"Adding the same number to BOTH the numerator and denominator brings the fraction CLOSER TO 1, regardless of the fraction's value"

In this problem I neglected to consider the case where T/F is not truly a fraction but instead simply a division operation of two variables where T > F, or a mixed number.

Thanks for helping me get smarter!
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 » Sun May 15, 2011 1:48 am
wayofjungle wrote:Is the number of seconds required to travel D feet at R feet per second greater than the number of seconds to travel T feet at F feet per second?

1. D is 30 greater than T
2. R is 30 greater than F

[spoiler]This is Q87 from OG12, OA is E, but I am convinced the answer is C. When both statements are combined the question becomes is (T+30)/(F+30) > T/F right? In that case the answer should be 'yes'. OG gives no explanation, so please enlighten me if you understand. Thanks[/spoiler]
Question: Is D/R > T/F?

Since the question is restricted to positive integers, we can cross-multiply and rephrase the question:

Is DF > RT?

Statement 1: D is 30 greater than T.
No information about F or R.
Insufficient.

Statement 2: R is 30 greater than F.
No information about D or T.
Insufficient.

Statements 1 and 2 combined:
D is 30 greater than T and R is 30 greater than F.
Is DF > RT?
Let T=1, D=31, F=1, R=31.
Is 31*1 > 31*1? No.
Let T=1, D=31, F=2, R=32.
Is 31*2 > 32*1? Yes.
Since the answer can be both No and Yes, insufficient.

The correct answer is E.
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
Legendary Member
Posts: 1077
Joined: Mon Dec 13, 2010 1:44 amFollowed by: 33 members
Thanked: 118 times
GMAT Score:710

by bblast » Sun May 15, 2011 5:37 am
this tests a fundamental concept of ratios.

"if the same number is added to the numerator and denominator a fraction:

1> if the fraction is proper the value of fraction increases
example
1/3 - add 1 to both num and denominator- fraction increases to 2/4


2> if the fraction is improper the value of fraction decreases"
example
3/2 - add 1 to both num and denominator- fraction decreases to 4/3


Hence in this solution we cannot say which of the fractions is larger.

(T+30)/(F+30)
OR
T/F



Mitch, please Correct me if I am wrong
Cheers !!

Quant 47-Striving for 50
Verbal 34-Striving for 40

My gmat journey :
https://www.beatthegmat.com/710-bblast-s ... 90735.html
My take on the GMAT RC :
https://www.beatthegmat.com/ways-to-bbla ... 90808.html
How to prepare before your MBA:
https://www.youtube.com/watch?v=upz46D7 ... TWBZF14TKW_
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1