Forum Home > GMAT > Quantitative > Problem Solving (PS)
Events & Promotions
|
|
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
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Dec 1310:00 AM EST
-12:00 PM EST
Have you ever wondered how to score a PERFECT 805 on the GMAT? Meet Julia, a banking professional who used the Target Test Prep course to achieve this incredible feat. Julia's story is nothing short of an inspiration.
Dec 1410:00 AM EST
-12:00 PM EST
Think a 100% GMAT Verbal score is out of your reach? Target Test Prep will make you think again! Our course uses techniques such as topical study and spaced repetition to maximize knowledge retention and make studying simple and fun.
Dec 1411:00 AM IST
-01:00 PM IST
Attend this session to learn how to Deconstruct arguments, Pre-Think Author’s Assumptions, and apply Negation Test.- Dec 15
11:00 AM IST
-01:00 PM IST
Attend this free GMAT Algebra Webinar and learn how to master the most challenging Inequalities and Absolute Value problems with ease. 
Dec 1608:00 AM PST
-11:59 PM PST
GMAT Club 12 Days of Christmas is a 4th Annual GMAT Club Winter Competition based on solving questions. This is the Winter GMAT competition on GMAT Club with an amazing opportunity to win over $40,000 worth of prizes!
19 Feb 2012, 07:30
Kudos
Bookmarks
A
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
35%
(medium)
Question Stats:
76% (02:49) correct
24%
(03:20)
wrong
based on 285
sessions
History
Date
Time
Result
Not Attempted Yet
Every student of a certain school must take one and only one elective course. In last year, 1/2 of the students took biology as an elective, 1/3 of the students took chemistry as an elective, and all of the other students took physics. In this year, 1/3 of the students who took biology and 1/4 of the students who took chemistry left school, other students did not leave, and no fresh student come in. What fraction of all students took biology and took chemistry?
A. 7/9
B. 6/7
C. 5/7
D. 4/9
E. 2/5
A. 7/9
B. 6/7
C. 5/7
D. 4/9
E. 2/5
19 Feb 2012, 07:37
Kudos
Bookmarks
Lets pick smart numbers. Total number of students: 12
Biology (1/2): 6
Chemistry (1/3): 4
Physics (1/6): 2
After leaving school
Biology: 4
Chemistry: 3
Physics: 2
New Total number of students: 9
Biology and Chemistry: 7
Answer 7/9 or A
Biology (1/2): 6
Chemistry (1/3): 4
Physics (1/6): 2
After leaving school
Biology: 4
Chemistry: 3
Physics: 2
New Total number of students: 9
Biology and Chemistry: 7
Answer 7/9 or A
General Discussion
05 Mar 2013, 21:11
Kudos
Bookmarks
I did in this way (was wrong earlier)
Biology = 1/2
Chemistry = 1/3
So, physics = 1 - (1/2+1/3) = 1/6
Biology students left = (1/2)/3 = 1/6. So remaining = 1/2 - 1/6 = 1/3 ------------- (i)
Chemistry students left = (1/3)/4 = 1/12. So remaining = 1/3 - 1/12 = 1/4 --------------- (ii)
Total Biology & Chemistry students left = (i) + (ii) = 7/12
Total all students left = 7/12 + 1/6 = 9/12 = 3/4
So the fraction comes up as (7/12) / (3/4) = 7/9
the
Biology = 1/2
Chemistry = 1/3
So, physics = 1 - (1/2+1/3) = 1/6
Biology students left = (1/2)/3 = 1/6. So remaining = 1/2 - 1/6 = 1/3 ------------- (i)
Chemistry students left = (1/3)/4 = 1/12. So remaining = 1/3 - 1/12 = 1/4 --------------- (ii)
Total Biology & Chemistry students left = (i) + (ii) = 7/12
Total all students left = 7/12 + 1/6 = 9/12 = 3/4
So the fraction comes up as (7/12) / (3/4) = 7/9
the
