Question type "Sets" (eg. OG13, no. 178)

This topic has expert replies
Junior | Next Rank: 30 Posts
Posts: 15
Joined: Fri Nov 09, 2012 3:48 am
Thanked: 1 times

Question type "Sets" (eg. OG13, no. 178)

by talueng » Wed Nov 14, 2012 9:19 pm
OG13, p.177, no. 178:
Of the 300 subjects who participated in an experiment [...], 40 percent experience sweaty palms, 30 percent experienced vomiting, and 75 percent experienced dizziness. If all of the subjects experienced at least one of these effects and 35 percent of the subjects experienced exactly two of these effects, how many of the subjects experienced only one of these effects?
This is a common question type and I am constantly struggling with it. Some of these question I can answer easily when you can use a table to visualize the dependencies of the different sets (see OG13 p.144 for an example). But then there questions of the same type where a table cannot be used.

Are there any general pointers or solutions how to tackle just questions?[/i]
Source: — Problem Solving |

User avatar
MBA Admissions Consultant
Posts: 2279
Joined: Fri Nov 11, 2011 7:51 am
Location: New York
Thanked: 660 times
Followed by:266 members
GMAT Score:770

by Jim@StratusPrep » Fri Nov 16, 2012 7:41 am
You can use a venn diagram with three sets here.

Tough to draw on this platform, but if you understand venn diagrams it will work well.
GMAT Answers provides a world class adaptive learning platform.
-- Push button course navigation to simplify planning
-- Daily assignments to fit your exam timeline
-- Organized review that is tailored based on your abiility
-- 1,000s of unique GMAT questions
-- 100s of handwritten 'digital flip books' for OG questions
-- 100% Free Trial and less than $20 per month after.
-- Free GMAT Quantitative Review

Image

User avatar
GMAT Instructor
Posts: 15539
Joined: Tue May 25, 2010 12:04 pm
Location: New York, NY
Thanked: 13060 times
Followed by:1906 members
GMAT Score:790

by GMATGuruNY » Fri Nov 16, 2012 12:41 pm
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

Senior | Next Rank: 100 Posts
Posts: 77
Joined: Tue Jul 31, 2012 6:53 am
Thanked: 8 times
Followed by:1 members

by GaneshMalkar » Sat Nov 17, 2012 3:32 am
I have done it with venn diagram

SP = 120
V = 90
D = 225

Exactly 2 = 105

and Exactly 3 = ?

Total - Neither = Sp + V + D - (exactly 2) - 2(Exactly 3)

300 - 0 = 120 + 90 + 225 - 105 - 2(Exactly 3)

Exactly 3 = 15

Exactly 1 = Total - Exactly 2 - Exactly 3
= 300 - 105 - 15 = 180

Hope this helps....
If you cant explain it simply you dont understand it well enough!!!
- Genius