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
Vote for Target Test Prep, Newsweek Readers’ Choice Awards 2026
NEWSWEEK READERS’ CHOICE 2026

BIG NEWS! Target Test Prep has been nominated, and they’d love your vote!

TTP has worked incredibly hard to build the best test prep experience possible, and winning Newsweek’s 2026 Readers’ Choice Award for Best Test Prep would mean a lot to them. If TTP has helped you, they’d be incredibly grateful for your vote. You can vote once each day through September 9.

Vote for TTP
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
40 hours of live online classes plus six months of access to the complete TTP EA OnDemand course.
  • 165+ EA Score Guarantee
  • 4,100+ Quant, Verbal, and Integrated Reasoning practice questions
  • 400+ hours of in-depth video lessons
  • 3,000+ step-by-step video solutions
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.

715+ 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.

Data Sufficiency

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Source: — Data Sufficiency |
Master | Next Rank: 500 Posts
Posts: 216
Joined: Mon Dec 21, 2009 10:26 am
Thanked: 16 times

by student22 » Wed Apr 07, 2010 6:00 pm
Is it A?

1/r + 1/s = 4 --> rs * (1/r + 1/s = 4) --> s + r = 4s. This is the same as statement 1. So that is sufficient.

Statement 2: Let's try:

1/s + 1/s = 2/s. Not sufficient, no idea what s is.

Let me know if I'm right.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Senior | Next Rank: 100 Posts
Posts: 65
Joined: Wed Nov 25, 2009 6:33 pm
Thanked: 3 times

by dxgamez » Wed Apr 07, 2010 6:54 pm
Right, A for me too.

1. s + r = 4rs, same as question, so sufficient

2. r-s = 0, if r & s are +ve fraction then ans to qn stem is true but if they are -ve fractions, then it would be false. so insufficient.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Senior | Next Rank: 100 Posts
Posts: 87
Joined: Wed Jan 06, 2010 8:16 pm
Location: Chandigarh, INDIA

by onedayi'll » Thu Apr 08, 2010 6:25 am
+1 A
Gym/GMAT/Girl -- Be Serious
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Junior | Next Rank: 30 Posts
Posts: 12
Joined: Fri Mar 26, 2010 11:57 am

by [email protected] » Thu Apr 08, 2010 7:49 am
If rs is not equal to 0, is 1/r + 1/s = 4,
can be simplified as (r+s)/rs=4

(1) r + s = 4rs
so
(r+s)/rs=4
=>4rs/rs=4
rs is cancelled, 4=4

insufficient

(2) r = s
so
(r+s)/rs=4
=>2r/rs=4
=>2/4=s
=>s=1/2
and r=1/2

(2) is sufficient, answer is B
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Junior | Next Rank: 30 Posts
Posts: 12
Joined: Fri Mar 26, 2010 11:57 am

by [email protected] » Thu Apr 08, 2010 7:53 am
oops, sorry, i missed the question details

(1 ) is sufficient to determine, 1/r+1/s=4, as r+s=4rs

so answer should be D
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Master | Next Rank: 500 Posts
Posts: 126
Joined: Wed Jun 24, 2009 1:12 pm
Location: Montreal
Thanked: 2 times
GMAT Score:510

by ssuarezo » Thu Apr 08, 2010 8:34 am
[email protected] wrote:oops, sorry, i missed the question details

(1 ) is sufficient to determine, 1/r+1/s=4, as r+s=4rs

so answer should be D
Yes, to me it's also D, each is sufficient.
What's the OA please?

Silvia
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Master | Next Rank: 500 Posts
Posts: 435
Joined: Mon Mar 15, 2010 6:15 amFollowed by: 1 member
Thanked: 32 times

by eaakbari » Thu Apr 08, 2010 8:46 am
[email protected] wrote:If rs is not equal to 0, is 1/r + 1/s = 4,
can be simplified as (r+s)/rs=4

(1) r + s = 4rs
so
(r+s)/rs=4
=>4rs/rs=4
rs is cancelled, 4=4

insufficient

(2) r = s
so
(r+s)/rs=4
=>2r/rs=4
=>2/4=s
=>s=1/2
and r=1/2

(2) is sufficient, answer is B

The answer should be A.
The mistake you are making is substituting the statement into what we have to prove.
The approach should be using the statement to prove the question
We are merely given r = s
take r and s as 5
1/5+1/5 is definitely not equal to 4
So statement two is insuff

Keep one thing in mind to avoid these mistakes, that in DS questions the statements will never contradict each other, if one says that x = 2 even the other should imply that. We merely have to decide whether the information will suffice ,it will never contradict
Whether you think you can or can't, you're right.
- Henry Ford
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Junior | Next Rank: 30 Posts
Posts: 12
Joined: Fri Mar 26, 2010 11:57 am

by [email protected] » Thu Apr 08, 2010 9:57 am
yep, you are right, I made a mistake understanding the question
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Legendary Member
Posts: 748
Joined: Sun Jan 31, 2010 7:54 amFollowed by: 3 members
Thanked: 46 times

by outreach » Thu Apr 08, 2010 10:10 am
1/r + 1/s =r+s/rs - eq1

A)

substituting r + s = 4rs in eq1
4rs/rs=4

hence sufficient

B) substitutin r = s in eq1
2r/r^2=2/r

value of r is not known hence insuffcient


vrowland wrote:If rs is not equal to 0, is 1/r + 1/s = 4,

(1) r + s = 4rs
(2) r = s




[/spoiler]
-------------------------------------
--------------------------------------
General blog
https://amarnaik.wordpress.com
MBA blog
https://amarrnaik.blocked/
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 8183
Joined: Sat Apr 25, 2015 10:56 amFollowed by: 29 members
Location: Los Angeles, CA
Thanked: 43 times

Re: Data Sufficiency

by Scott@TargetTestPrep » Wed Jun 30, 2021 10:53 am
vrowland wrote: ↑
Wed Apr 07, 2010 5:48 pm
 If rs is not equal to 0, is 1/r + 1/s = 4,

(1) r + s = 4rs
(2) r = s




[/spoiler]
Solution:

Question Stem Analysis:

We need to determine whether 1/r + 1/s = 4, i.e., (r + s)/(rs) = 4.

Statement One Alone:

Since r + s = 4rs, we have (r + s)/(rs) = (4rs)/(rs) = 4. Statement one alone is sufficient.

Statement Two Alone:

Statement two is not sufficient. For example, if r = s = 1/2, 1/r + 1/s = 2 + 2 = 4. However, if r = s = 1, 1/r + 1/s = 1 + 1 = 2.

Answer: A

Scott Woodbury-Stewart
Founder and CEO
[email protected]

Image

See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews

ImageImage
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1