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 →

Scoops of ice cream

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 » Tue Mar 29, 2011 7:00 pm
At a picnic, each of the guests was served either a single scoop or double scoop of ice cream. How many of the guests were served a double scoop of ice cream?

1. At the picnic, 60 percent of the guests were served a double scoop of ice cream.

2. A total of 120 scoops of ice cream were served to all the guests at the picnic.


I got the answer correct, but can someone walk me through the algebra so that I work on my algebraic translations. Thanks.

OA = C
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Data Sufficiency |

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 3835
Joined: Fri Apr 02, 2010 10:00 pmFollowed by: 523 members
Location: Milpitas, CA
Thanked: 1854 times
GMAT Score:770

by Anurag@Gurome » Tue Mar 29, 2011 7:24 pm
tonebeeze wrote:At a picnic, each of the guests was served either a single scoop or double scoop of ice cream. How many of the guests were served a double scoop of ice cream?

1. At the picnic, 60 percent of the guests were served a double scoop of ice cream.

2. A total of 120 scoops of ice cream were served to all the guests at the picnic.


I got the answer correct, but can someone walk me through the algebra so that I work on my algebraic translations. Thanks.

OA = C
Let no. of guests who are served single scoop = S
Let no. of guests who are served double scoop = D
So, total no. of guests = S + D

(1) D = 0.60(S + D), one equation, two variables. So, (1) is NOT SUFFICIENT.
(2) S + D = 120, one equation, two variables. So, (2) is NOT SUFFICIENT.

Combining (1) and (2), we get 0.4D = 0.6S and S + D = 120, we have 2 equation, 2 variables, which can be solved to find D. Hence, SUFFICIENT.
The correct answer is C.
Anurag Mairal, Ph.D., MBA
GMAT Expert, Admissions and Career Guidance
Gurome, Inc.
1-800-566-4043 (USA)

Join Our Facebook Groups
GMAT with Gurome
https://www.facebook.com/groups/272466352793633/
Admissions with Gurome
https://www.facebook.com/groups/461459690536574/
Career Advising with Gurome
https://www.facebook.com/groups/360435787349781/
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 Mar 30, 2011 12:40 am
tonebeeze wrote:At a picnic, each of the guests was served either a single scoop or double scoop of ice cream. How many of the guests were served a double scoop of ice cream?

1. At the picnic, 60 percent of the guests were served a double scoop of ice cream.

2. A total of 120 scoops of ice cream were served to all the guests at the picnic.
.
Anurag's approach is great for anyone comfortable with the algebra. Please note, however, that the equation for statement 2 should be S + 2D = 120:
Total number of scoops = 120.
S = number of scoops served to the single-scoop guests.
2D = number of scoops served to the double-scoop guests.
Thus, S + 2D = 120.

Here's an approach that bypasses the algebra:

Statement 1: 60 percent of the guests were served a double scoop.
Plug in a number in order to determine what fraction of the scoops were served to the double-scoop guests.
Let guests = 10.
Then .6*10 = 6 guests were served a double scoop, 10-6 = 4 guests were served a single scoop.
The number of scoops served to the 6 double-scoop guests = 2*6 = 12, the number of scoops served to the 4 single-scoop guests = 1*4 = 4.
Total scoops = 12+4 = 16.
Thus, the double-scoop guests were served 12/16 = 3/4 of the scoops.
No way to determine the number of double-scoop guests.
Insufficient.

Statement 2: A total of 120 scoops were served.
No way to determine the number of double-scoop guests.
Insufficient.

Statements 1 and 2 combined:
The double-scoops guests were served 3/4 * 120 = 90 scoops.
Since each double-scoop guest was served 2 scoops, the number of double-scoop guests = 90/2 = 45.
Sufficient.

The correct answer is C.
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
Senior | Next Rank: 100 Posts
Posts: 51
Joined: Wed Jan 05, 2011 3:32 amFollowed by: 1 member

by Strongt » Wed May 04, 2011 2:06 am
Is it a rule of thumb that whenever we have an unknown varibable, we need two linear equations to solve for the unknown?
I get similar questions a lot on DS and I find it to be my weakness point.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Senior | Next Rank: 100 Posts
Posts: 57
Joined: Fri Jan 14, 2011 10:01 am
Thanked: 10 times

by djiddish98 » Thu May 05, 2011 12:34 pm
Strongt wrote:Is it a rule of thumb that whenever we have an unknown varibable, we need two linear equations to solve for the unknown?
I get similar questions a lot on DS and I find it to be my weakness point.
Look out for when the DS is setup like this...

What is 2x + 3y?

Statement 1 - 4x+6y = 8

There are two variables, but if you divide statement 1 by 2, you end up solving for 2x+3y.

For this question - I got a little thrown by the wording. When it asked for how many, I thought at first that 60% could be an answer. Perhaps something like "what is the total number of guests that received 2 scoops" would be better language.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1