College students

Expert replies

zaarathelab: Master | Next Rank: 500 Posts; Posts: 217; Joined: Sun Jan 10, 2010 1:39 pmFollowed by: 1 member; Thanked: 7 times

by zaarathelab » Sat Oct 15, 2011 1:29 am

In a sample of college students, 40 percent are third-year students and 70 percent are not second-year students. What fraction of those students who are not third-year students are second-year students?

(A) 3/4
(B) 2/3
(C) 4/7
(D) 1/2
(E) 3/7

I setup the double matrix correctly (SEE ATTACHMENT), but i got lost in the final line of the problem. Can someone explain the last line? Don't we have to find a?

You do not have the required permissions to view the files attached to this post.

Success = Max(Hardwork) + Min(Luck)

Source: Beat The GMAT — Problem Solving | Sat Oct 15, 2011 1:29 am

sl750: Master | Next Rank: 500 Posts; Posts: 496; Joined: Tue Jun 07, 2011 5:34 amFollowed by: 1 member; Thanked: 38 times

by sl750 » Sat Oct 15, 2011 1:50 am

Going by your double matrix diagram a=30 . So 30/60 = 1/2. The case of a student being both in the second and third year is not possible, hence it is zero

Percentage of students who are NOT third year = 60
Percentage of students who are second year = 30

So 30/60 is the fraction who are NOT third year but second year students

jayavignesh: Senior | Next Rank: 100 Posts; Posts: 45; Joined: Tue Mar 30, 2010 7:00 pm

by jayavignesh » Sat Oct 15, 2011 3:23 am

zaarathelab wrote:In a sample of college students, 40 percent are third-year students and 70 percent are not second-year students. What fraction of those students who are not third-year students are second-year students?

(A) 3/4
(B) 2/3
(C) 4/7
(D) 1/2
(E) 3/7

I setup the double matrix correctly (SEE ATTACHMENT), but i got lost in the final line of the problem. Can someone explain the last line? Don't we have to find a?

Please forget about the matrix .Go by percentages.
Look for information that can be withdrawn from the statements given.
statement 1: 60% are not third year students.
statement 2: 30% may or may not be second year students from the pool of 60 %

So it is 30% out of 60% i.e., (30/60)=(1/2)

Ans:D

rohit_gmat: Master | Next Rank: 500 Posts; Posts: 158; Joined: Wed Jun 16, 2010 8:21 amFollowed by: 1 member; Thanked: 13 times

by rohit_gmat » Sat Oct 15, 2011 5:07 am

plug-in....

100 is a good number.
so # of 3rd yr students = 40
# of NOT 2nd yr students = 70

& so # of 2nd yr students = 30
# of students who are not 3rd students = 100 - 40 = 60
fraction = 30/60 = 1/2

D

zaarathelab: Master | Next Rank: 500 Posts; Posts: 217; Joined: Sun Jan 10, 2010 1:39 pmFollowed by: 1 member; Thanked: 7 times

by zaarathelab » Sat Oct 15, 2011 7:17 am

OA is D

Success = Max(Hardwork) + Min(Luck)

Featured schoolRound 2 closes Jan 7, 2027 53 days left

Chicago Booth

Since 1982, 10 Booth faculty members have received the Nobel Prize in Economic Sciences, more than any other business school.

#3
U.S. News rank: $175,000
Median base salary: 670
Average GMAT Focus: 635
Students in the class

Apply to Booth Visit chicagobooth.edu See the full profile

Photo: Warren LeMay, CC BY-SA 2.0

GMAT Course Reviews

563 reviews

1168 reviews

431 reviews

359 reviews

147 reviews

5/5

5 Star (563 Reviews)

"Target Test Prep is the closest to the official version of the GMAT exam, about 99% accuracy in terms of the quality and quantity of information. The course has excellently created singular sets of focused lessons and tests for every possible topic that one could come across in the official GMAT exam."

"The TTP course maximizes the efficiency of the time you spend studying. It will take time and effort but I could almost guarantee that if you complete the course exactly as it is laid out you will get an amazing score. They also have a very responsive team willing to help with any questions you might have."

"TTP has two things that I think no other test prep company offers: A teaching approach that reinforces understanding and an attitude that will give you the mental preparedness needed to succeed on the test. TTP gives you a deep understanding of the concept you need to know while teaching you how to think."

Write a Review