GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 17 Feb 2019, 20:34

Close

GMAT Club Daily Prep

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.

Close

Request Expert Reply

Confirm Cancel
Events & Promotions in February
PrevNext
SuMoTuWeThFrSa
272829303112
3456789
10111213141516
17181920212223
242526272812
Open Detailed Calendar
  • Free GMAT Algebra Webinar

     February 17, 2019

     February 17, 2019

     07:00 AM PST

     09:00 AM PST

    Attend this Free Algebra Webinar and learn how to master Inequalities and Absolute Value problems on GMAT.
  • Valentine's day SALE is on! 25% off.

     February 18, 2019

     February 18, 2019

     10:00 PM PST

     11:00 PM PST

    We don’t care what your relationship status this year - we love you just the way you are. AND we want you to crush the GMAT!

A science lab is conducting an experiment monitoring the appearance of

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

 
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 52907
A science lab is conducting an experiment monitoring the appearance of  [#permalink]

Show Tags

New post 31 Mar 2017, 03:00
3
7
00:00
A
B
C
D
E

Difficulty:

  45% (medium)

Question Stats:

64% (01:57) correct 36% (02:30) wrong based on 148 sessions

HideShow timer Statistics

A science lab is conducting an experiment monitoring the appearance of genetic traits in laboratory rats. Of the three traits being monitored all of the animals bear at least one of the three traits being monitored, one third of the rats were obese, three fourths of the rats had white fur, and one half of the rats had an elongated mandible. How many had all three of these traits?

(1) Of the 120 rats in the experiment, 40 had white fur and an elongated mandible.
(2) Of the 120 rats in the experiment, 40 had exactly two of the traits.

_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics

Most Helpful Community Reply
Manager
Manager
User avatar
S
Joined: 21 Jul 2017
Posts: 192
Location: India
Concentration: Social Entrepreneurship, Leadership
GMAT 1: 660 Q47 V34
GPA: 4
WE: Project Management (Education)
Premium Member Reviews Badge
Re: A science lab is conducting an experiment monitoring the appearance of  [#permalink]

Show Tags

New post 05 Oct 2017, 08:45
4
1
A useful formula for 3 overlapping groups:

T = A + B + C - (AB + AC + BC) - 2(ABC)

The big idea with overlapping group problems is to SUBTRACT THE OVERLAPS.
When we add together everyone in A, everyone in B, and everyone in C:
Those in exactly 2 of the groups (AB+AC+BC) are counted twice, so they need to be subtracted from the total ONCE.
Those in all 3 groups (ABC) are counted 3 times, so they need to be subtracted from the total TWICE.
By subtracting the overlaps, we ensure that no one is overcounted.

In the problem above:
Let T = 120.
Obese = (1/3)(120) = 40.
White fur = (3/4)(120) = 90.
Elongated mandible = (1/2)(120) = 60.
Exactly 2 of the groups = OW + OE + WE.
All 3 groups = OWE.

Plugging these values into the formula, we get:
120 = 40 + 90 + 60 - (OW + OE + WE) - 2(OWE)
-70 = - (OW + OE + WE) - 2(OWE)
(OW + OE + WE) + 2(OWE) = 70.

Since the least possible value for (OW + OE + WE) is 0, the greatest possible value for OWE is 35.

Statement 1:
Of the 120 rats in the experiment, 40 had white fur and an elongated mandible.
Case 1: Of these 40 rats, 5 have all 3 traits (OWE=5), implying that 35 have only white fur and an elongated mandible (WE=35).
Case 2: Of these 40 rats, 10 have all 3 traits (OWE=10), implying that 30 have only white fur and an elongated mandible (WE=30).
Since OWE can be different values, INSUFFICIENT.

Statement 2:
Of the 120 rats in the experiment, 40 had exactly two of the traits.
Substituting (OW + OE + WE) = 40 into (OW + OE + WE) + 2(OWE) = 70, we get:
40 + 2(OWE) = 70.
2(OWE) = 30
OWE = 15.
SUFFICIENT.

The correct answer is B.
General Discussion
SC Moderator
User avatar
D
Joined: 13 Apr 2015
Posts: 1687
Location: India
Concentration: Strategy, General Management
GMAT 1: 200 Q1 V1
GPA: 4
WE: Analyst (Retail)
GMAT ToolKit User Premium Member
Re: A science lab is conducting an experiment monitoring the appearance of  [#permalink]

Show Tags

New post 31 Mar 2017, 21:28
2
Number of 3 overlaps = ?

Exactly one + Exactly two overlaps + Exactly 3 overlaps = 120 -------(1)
Exactly one + 2(Exactly two overlaps) + 3(Exactly 3 overlaps) = 40 + 90 + 60 = 190 -------(2)
(2) - (1) = Exactly two overlaps + 2(Exactly 3 overlaps) = 70
To find the number of 3 overlaps we need the value of exactly two overlaps.

St1: Of the 120 rats in the experiment, 40 had white fur and an elongated mandible. --> Not Sufficient as we do not know the overlaps between white fur and obese, and between obese and elongated mandible.

St2: Exactly two overlaps = 40 --> 3 overlaps = (70 - 40)/2 = 15.
Sufficient.

Answer: B
Non-Human User
User avatar
Joined: 09 Sep 2013
Posts: 9839
Premium Member
Re: A science lab is conducting an experiment monitoring the appearance of  [#permalink]

Show Tags

New post 13 Oct 2018, 04:13
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________

GMAT Books | GMAT Club Tests | Best Prices on GMAT Courses | GMAT Mobile App | Math Resources | Verbal Resources

GMAT Club Bot
Re: A science lab is conducting an experiment monitoring the appearance of   [#permalink] 13 Oct 2018, 04:13
Display posts from previous: Sort by

A science lab is conducting an experiment monitoring the appearance of

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


Copyright

GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.