Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.
Customized for You
we will pick new questions that match your level based on your Timer History
Track Your Progress
every week, we’ll send you an estimated GMAT score based on your performance
Practice Pays
we will pick new questions that match your level based on your Timer History
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:
Meet 50 MBA & MiM programs in only 3 days! MBA Spotlight - a dedicated Business School event to bring MBA and MiM applicants and World’s Top Business Schools together for a Packed 3-day experience of getting to know MBA programs and more.
Take 20% off all Manhattan Prep GMAT courses for a limited time! Use code THANKS20 at checkout. This discount is only available from November 24-29 Valid on Complete Course, Interact® On-Demand Course, Advanced Course, and Executive Assessment Course.
In the last 2 years, GMATWhiz has delivered the highest score improvement in the industry. Buy our online course & get access to a personalized study plan, 100+ video lessons, 4000+ questions, 10 mocks & a dedicated mentor, at lowest ever price of $199
Try Target Test Prep and see for yourself how we’re changing the way students prepare for the GMAT. 20% off on any of our GMAT plans. Coupon Code TTPBlackFriday
Join us in the launch event of P.A.C.E (Personalized Adaptive Course Engine), the next generation of Personalized Learning that will change how you prepare for the GMAT. P.A.C.E allows you to become a more effective learner, help save time, and more.
We offer a 110-Point score improvement guarantee, and we are so confident you will have success with our course that we guarantee it. Need a higher GMAT score? For $1, you can sign up for a 5-Day full-access trial of TTP’s 5-star rated GMAT course.
Attend this webinar to learn how to leverage meaning and logic to solve the most challenging (700+ level) Sentence Correction Questions with 90+ % Accuracy
70%
(02:32)
correct
30%
(02:51)
wrong
based on 279
sessions
HideShow
timer Statistics
A group of 20 people are drinking coffee. The total number taking cream in their coffee is 7 less than twice the total number taking sugar. The number taking both cream and sugar is the same as the number taking neither. How many people in the group take cream?
A group of 20 people are drinking coffee. The total number taking crea
[#permalink]
23 May 2020, 12:24
2
Kudos
6
Bookmarks
Expert Reply
Top Contributor
Bunuel wrote:
A group of 20 people are drinking coffee. The total number taking cream in their coffee is 7 less than twice the total number taking sugar. The number taking both cream and sugar is the same as the number taking neither. How many people in the group take cream?
A. 9 B. 10 C. 11 D. 12 E. 13 PS20487
One approach is to use the Double Matrix Method. This technique can be used for questions featuring a population in which each member has two characteristics associated with it (aka overlapping sets questions).
Here, we have a population of coffee drinkers, and the two characteristics are: - takes cream or does not take cream - takes sugar or does not take sugar
Aside: We can also use Venn diagrams and formulae to solve overlapping sets questions. However, as difficulty levels increase, it becomes harder to apply those other approaches, whereas the Double Matrix Method works every time.
20 people are drinking coffee. The total number taking cream in their coffee is 7 less than twice the total number taking sugar. The number taking both cream and sugar is the same as the number taking neither. Let x = the number of people taking sugar This means 2x - 7 = the number of people taking cream
Let k = the number of people taking both cream and sugar So, k = the number of people taking neither cream nor sugar
We get the following:
There are 20 people in total. So, if x of them are taking sugar, then 20 - x of them are NOT taking sugar
Likewise, if (2x - 7) of them are taking cream, then 20 - (2x - 7) of them are NOT taking cream Simplify to get: 27 - 2x of them are NOT taking cream
Add this to our diagram to get:
Now let's focus on the value in the TOP-RIGHT box Since the two boxes in the RIGHT-HAND column add to 20 - x, we can conclude that (20 - x) - k is the value in the TOP-RIGHT box
Likewise, since the two boxes in the TOP row add to 2x - 7, we can conclude that (2x - 7) - k is the value in the TOP-RIGHT box
Notice that we have two different ways to express the value in the TOP-RIGHT box So, it must be the case that those quantities are equal In other words: (20 - x) - k = (2x - 7) - k Simplify each side: 20 - x - k = 2x - 7 - k Add k to both sides: 20 - x = 2x - 7 Add x to both sides: 20 = 3x - 7 Add 7 to both sides: 27 = 3x Solve: x = 9
How many people in the group take cream? We already know that 2x - 7 people take cream Since x = 9, the number of people who take cream = 2(9) - 7 = 11
Answer: C
This question type is VERY COMMON on the GMAT, so be sure to master the technique.
To learn more about the Double Matrix Method, watch this video:
Re: A group of 20 people are drinking coffee. The total number taking crea
[#permalink]
22 May 2020, 15:20
1
Kudos
let "c" represents total number of people taking cream let "s" represents total number of people taking sugar let "cs" represents total number of people taking cream+ sugar let "n" represents total number taking niether.
given, I. total number taking cream in their coffee is 7 less than twice the total number taking sugar ==> c=2s-7 ------------ (i)
II. The number taking both cream and sugar is the same as the number taking neither ==> cs=n ----------(ii)
III. A group of 20 people are drinking coffee ==> c+s-cs+n = 20 -----------(iii) putting (ii) in (iii) we get==> c+s=20 --------------- (iv) putting value of c from (i) in (iv) we get 2s-7+s=20 or s= 9 -------- (v) putting value of s(=9) in (iv) or (i) we get c=11 = answer= option C
Re: A group of 20 people are drinking coffee. The total number taking crea
[#permalink]
30 May 2020, 08:06
1
Kudos
Expert Reply
Solution
Given
In this question, we are given that
• A group of 20 people are drinking coffee • The total number taking cream in their coffee is 7 less than twice the total number taking sugar • The number taking both cream and sugar is the same as the number taking neither
To find We need to determine
• The number of people, in the group, who take cream
Approach and Working out
• Number of people who drink coffee = 20
o Number of people who drink coffee with sugar = x o Number of people who drink coffee with cream = 2x - 7 o Number of people who drink only coffee = y o Number of people who drink coffee with both cream and sugar = y
Re: A group of 20 people are drinking coffee. The total number taking crea
[#permalink]
03 Jun 2020, 12:46
Number of people who drink coffee = 20 Number of people who drink coffee with sugar = S Number of people who drink coffee with cream,C = 2S - 7 No of people with both = No of people with neither = Y
If we work with options, we realize that C has to be odd : because : even C = 2S-7 , shall give in S in decimal which is not possible : e.g : C=12 :S will be: 19/2, not possible Only odd answers A,C,E 9= 2s-7 : S = 8 C+S = 17, But not possible,as 20-17 :3 /y =1.5
these types of questions can be solved either by venn diagram or by 2 table
how to distinguish , which one to be chose?
Actually double matrix is the extension of the vent diagram. The Venn diagram of two circles will have 4 zones Outside both the circles —- none of the two Overlap — common to the two Area under a single circle — only one
Exactly the same 4 areas are there in 2*2 matrix.
You can use any which you find comfortable. _________________
Re: A group of 20 people are drinking coffee. The total number taking crea
[#permalink]
24 Oct 2020, 03:10
Dear Chetan !!!
Thanks for your reply.
Actually intent for asking this question is that I started solving these questions from the Venn diagram and if I am unable to get the answer from it within 1 min or so, then I try the 2X2 Matrix.
but both seem to be the same. actully am loosing about 1 min to find out which one to be used.
these types of questions can be solved either by venn diagram or by 2 table
how to distinguish , which one to be chose?
Actually double matrix is the extension of the vent diagram. The Venn diagram of two circles will have 4 zones Outside both the circles —- none of the two Overlap — common to the two Area under a single circle — only one
Re: A group of 20 people are drinking coffee. The total number taking crea
[#permalink]
01 Dec 2020, 18:52
Total number of people drinking coffee = 20 Total number of people who use cream = 2x - 7 Total number of people who use sugar = x
Therefore we can conclude the total number of people who DON'T use sugar = 20 - x Therefore we can conclude the total number of people who DON'T use cream = 20 - (2x-7) = 27 - 2x
The number taking both cream and sugar is the same as the number taking neither. Let this number = n
What is 2x - 7?
We need to find the value of x. We can create the following equation:
\((20 - x) - n = (2x-7) - n\)
\(27 = 3x\)
\(9 = x\)
\(2(9) - 7 = 11\)
Answer is C. _________________
Help me get better -- please critique my responses!
One of the fastest-growing graduate business schools in Southern California, shaping the future by developing leading thinkers who will stand at the forefront of business growth. MBA Landing | School of Business (ucr.edu)