In a given finance lecture, 30% of the students are finance

Expert replies

vinni.k: Master | Next Rank: 500 Posts; Posts: 421; Joined: Sun Apr 17, 2011 4:27 amFollowed by: 2 members; Location: India; Thanked: 6 times; GMAT Score:620

by vinni.k » Wed Mar 14, 2018 7:33 am

In a given finance lecture, 30% of the students are finance majors, and 40% of the students are female. The gender distribution for finance majors and non-finance majors is the same. If one student is called on at random, what is the probability that the student is neither female nor a finance major?

A. 70%
B. 60%
C. 58%
D. 42%
E. 30%

OA is D

My confusion:- The gender distribution for finance majors and non-finance majors is the same.

My approach :- I somehow got this question by creating a set matrix table and doing educated guessing via eliminating A,B, and C
I am confused on the highlighted line above. Can you please elaborate on this line ?

Thanks

Like this post

Source: Beat The GMAT — Problem Solving | Wed Mar 14, 2018 7:33 am

GMAT/MBA Expert

ErikaPrepScholar: Legendary Member; Posts: 503; Joined: Thu Jul 20, 2017 9:03 amFollowed by: 15 members; Thanked: 86 times; GMAT Score:770

by ErikaPrepScholar » Wed Mar 14, 2018 7:54 am

If the distribution of gender for finance majors and non-finance majors is the same, then 40% of finance majors are female and 40% of non-finance majors are female. This simplifies the problem dramatically.

So if 30% of the students are finance majors, this means that 70% are NOT finance majors. Then, if 40% of those non-finance majors are female, 60% of those non-finance majors are NOT female. So if we take 60% of 70%, we'll get the total number of students that are NOT finance majors and NOT female. 0.6*0.7=0.42, so 42% is our answer.

The double matrix is a great tool, but it isn't always necessary or the best way to get to the answer - try to use logic to interpret the question first, then decide whether or not it's the best method to solve.

Erika John - Content Manager/Lead Instructor
https://gmat.prepscholar.com/gmat/s/

Get tutoring from me or another PrepScholar GMAT expert: https://gmat.prepscholar.com/gmat/s/tutoring/

Learn about our exclusive savings for BTG members (up to 25% off) and our 5 day free trial

Check out our PrepScholar GMAT YouTube channel, and read our expert guides on the PrepScholar GMAT blog

Like this post

GMAT/MBA Expert

Brent@GMATPrepNow: GMAT Instructor; Posts: 16207; Joined: Mon Dec 08, 2008 6:26 pmFollowed by: 1268 members; Location: Vancouver, BC; Thanked: 5254 times; GMAT Score:770

by Brent@GMATPrepNow » Wed Mar 14, 2018 8:13 am

vinni.k wrote:In a given finance lecture, 30% of the students are finance majors, and 40% of the students are female. The gender distribution for finance majors and non-finance majors is the same. If one student is called on at random, what is the probability that the student is neither female nor a finance major?

A. 70%
B. 60%
C. 58%
D. 42%
E. 30%

This question can be solved using the Double Matrix method.

Note: This technique can be used for most questions featuring a population in which each member has two criteria associated with it.
Here, the criteria are:
- Major (Finance or Non-Finance)
- Gender (Female or Male)

Since we're dealing with percents all the way through to the answer choices, let's make things easy on ourselves and say that there are 100 students in the lecture.
So, here's the setup.

30% of the students are finance majors
So, 30 students are finance majors and 70 are not.

40% of the students are female
We get:

The gender distribution for finance majors and non-finance majors is the same.
In other words, there's a 40/60 female/male split among the finance majors and among the non-finance majors.
We get:

What is the probability that the student is neither female nor a finance major?
In other words, what is the probability that the student is a male non-finance major?
Once we simplify the boxes . . .

Brent Hanneson - Creator of GMATPrepNow.com

Like this post

vinni.k: Master | Next Rank: 500 Posts; Posts: 421; Joined: Sun Apr 17, 2011 4:27 amFollowed by: 2 members; Location: India; Thanked: 6 times; GMAT Score:620

by vinni.k » Wed Mar 14, 2018 11:27 am

Brent and Erika,

Thanks for your reply. Appreciate it <i class="em em-blush"></i>

Like this post

swerve: Legendary Member; Posts: 2535; Joined: Sun Oct 29, 2017 2:04 pmFollowed by: 6 members

by swerve » Thu Mar 15, 2018 10:33 am

Hi vinni.k,

Here's my solution,

Ratio of male to female to total= 6:4:10.

Total non-finance students= 100-30=70.

Since the gender distribution is same. i.e.: 6:4.

Male:female of non- finance students = 42:28.

Probability = 42/100= 42%. Option D.

Regards!

Like this post

Post new topic Post Reply

• Page 1 of 1

GMAT Course Reviews

559 reviews

1168 reviews

431 reviews

359 reviews

147 reviews

5/5

5 Star (560 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