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 →

Convention Attendees

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Master | Next Rank: 500 Posts
Posts: 158
Joined: Mon Nov 02, 2009 5:49 pmFollowed by: 3 members
Thanked: 2 times
by tonebeeze » Sun Jan 02, 2011 9:05 pm
The attendees at a certain convention purchased a total of 15,000 books. How many of these attendees were female?

1. There was a total of 4, 000 attendees at the convention.

2. The male attendees purchased an average (arithmetic mean) of 3 books each, and the females purchased an average of 5 books each.

I would appreciate it if someone could walk me through this problem. Thanks.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Data Sufficiency |
User avatar
Legendary Member
Posts: 543
Joined: Tue Jun 15, 2010 7:01 pmFollowed by: 3 members
Thanked: 147 times

by anshumishra » Sun Jan 02, 2011 9:11 pm
tonebeeze wrote:The attendees at a certain convention purchased a total of 15,000 books. How many of these attendees were female?

1. There was a total of 4, 000 attendees at the convention.

2. The male attendees purchased an average (arithmetic mean) of 3 books each, and the females purchased an average of 5 books each.

I would appreciate it if someone could walk me through this problem. Thanks.
x -> men
y-> women
Total books sold = 15000
y = ?

Statement 1 :
x+y = 4000

Insufficient

Statement 2:
3x+5y = 15000 -> Insufficient

Combining 1 and 2 :

Two independent equations in x and y, hence sufficient.

C
Thanks
Anshu

(Every mistake is a lesson learned )
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Newbie | Next Rank: 10 Posts
Posts: 1
Joined: Mon Feb 24, 2014 7:52 pm

by brian91480 » Mon Feb 24, 2014 7:58 pm
I don't understand why this is unsolvable. Help me to understand. What is wrong with this logic:

x + y = 4,000
3x + 5y = 15,000

Multiply the first equation by (-3) and you get: -3x - 3y = -12,000

Now combine the equations:

-3x - 3y = -12,000
3x + 5y = 15,000
2y = 3,000
y = 1,500

Women in attendance: 1,500..... Men in attendance: 2,500

Check the solution with information in the original question:

4,000 total attendees, 15,000 books were sold, women each bought 5 books on average, men bought 3 books on average:

1,500 women x 5 books per woman = 7,500 books sold
2,500 men x 3 books per man = 7,500 books sold

Total attendees: 4,000...... total books sold: 15,000

The equation seems solved..... where am I going wrong?

Thx,

Brian
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
GMAT Instructor
Posts: 1248
Joined: Thu Mar 29, 2012 2:57 pmFollowed by: 192 members
Location: Everywhere
Thanked: 503 times
GMAT Score:780

by Bill@VeritasPrep » Mon Feb 24, 2014 8:35 pm
Where are you seeing that it is unsolvable? I agree that it should be C, though I used a different method to get there.
Join Veritas Prep's 2010 Instructor of the Year, Matt Douglas for GMATT Mondays

Visit the Veritas Prep Blog

Try the FREE Veritas Prep Practice Test
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY

GMAT/MBA Expert

User avatar
Elite Legendary Member
Posts: 10392
Joined: Sun Jun 23, 2013 6:38 pmFollowed by: 511 members
Location: Palo Alto, CA
Thanked: 2867 times
GMAT Score:800

by [email protected] » Mon Feb 24, 2014 9:11 pm
Hi brian91480,

Every DS question has at least 1 solution. The information in the two Facts that follow the prompt can help you to narrow down the possibilities. If there's just 1 answer, then a given Fact is SUFFICIENT. If there's more than 1 (meaning "different") answers, then a given Fact is INSUFFICIENT.

Here, both Fact 1 and Fact 2, when dealt with individually, would lead to multiple answers. Thus, they're both INSUFFICIENT.

Combining Facts, as you've seen/solved, produces just 1 answer. So, the Facts are COMBINED SUFFICIENT.

Final Answer: C

GMAT assassins aren't born, they're made,
Rich
Contact Rich at [email protected]
Image
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1