• Free Veritas GMAT Class
Experience Lesson 1 Live Free

Available with Beat the GMAT members only code

• Magoosh
Study with Magoosh GMAT prep

Available with Beat the GMAT members only code

• Award-winning private GMAT tutoring
Register now and save up to $200 Available with Beat the GMAT members only code • 5 Day FREE Trial Study Smarter, Not Harder Available with Beat the GMAT members only code • Free Trial & Practice Exam BEAT THE GMAT EXCLUSIVE Available with Beat the GMAT members only code • 5-Day Free Trial 5-day free, full-access trial TTP Quant Available with Beat the GMAT members only code • Get 300+ Practice Questions 25 Video lessons and 6 Webinars for FREE Available with Beat the GMAT members only code • FREE GMAT Exam Know how you'd score today for$0

Available with Beat the GMAT members only code

• Free Practice Test & Review
How would you score if you took the GMAT

Available with Beat the GMAT members only code

• 1 Hour Free
BEAT THE GMAT EXCLUSIVE

Available with Beat the GMAT members only code

## Another probability question..making mistakes!

This topic has 2 expert replies and 4 member replies
dddanny2006 Master | Next Rank: 500 Posts
Joined
12 Jan 2012
Posted:
209 messages

#### Another probability question..making mistakes!

Thu Nov 21, 2013 3:10 pm
In a certain corporation, there are 300 male employees and 100 female employees. It is known that 20% of the male employees have advanced degrees and 40% of the females have advanced degrees. If one of the 400 employees is chosen at random, what is the probability this employee has an advanced degree or is female?

A)1/20
B)1/10
C)1/5
D)2/5
E)3/4

I did it this way- P(Advanced degree) OR P(Female)
(100/400)+(100/400) =1/2

I have not been able to apply the Manhattan Concepts in this problem.Im finding probability difficult,please advice on going about it.

Thanks

### GMAT/MBA Expert

GMATGuruNY GMAT Instructor
Joined
25 May 2010
Posted:
14182 messages
Followed by:
1820 members
13060
GMAT Score:
790
Thu Nov 21, 2013 5:58 pm
dddanny2006 wrote:
In a certain corporation, there are 300 male employees and 100 female employees. It is known that 20% of the male employees have advanced degrees and 40% of the females have advanced degrees. If one of the 400 employees is chosen at random, what is the probability this employee has an advanced degree or is female?

A)1/20
B)1/10
C)1/5
D)2/5
E)3/4
P = (good outcomes)/(all possible outcomes).

Here, it might be easier to count each part of the fraction separately.

All:
There are 400 employees.
Thus, the total number of possible outcomes = 400.

Good outcomes:
Of these 400 employees, any employee who is female or who has an advanced degree will constitute a good outcome.
Females = 100.
Since 20% of the men have advanced degrees, males with advanced degrees = .2(300) = 60.
Thus:
The total number of good outcomes = 100+60 = 160.

Resulting probability:
good/all = 160/400 = 16/40 = 2/5.

The correct answer is D.

_________________
Mitch Hunt
GMAT Private Tutor
GMATGuruNY@gmail.com
If you find one of my posts helpful, please take a moment to click on the "UPVOTE" icon.
Available for tutoring in NYC and long-distance.

Free GMAT Practice Test How can you improve your test score if you don't know your baseline score? Take a free online practice exam. Get started on achieving your dream score today! Sign up now.
Uva@90 Master | Next Rank: 500 Posts
Joined
04 Jul 2013
Posted:
490 messages
Followed by:
5 members
83
Thu Nov 21, 2013 7:32 pm
dddanny2006 wrote:
In a certain corporation, there are 300 male employees and 100 female employees. It is known that 20% of the male employees have advanced degrees and 40% of the females have advanced degrees. If one of the 400 employees is chosen at random, what is the probability this employee has an advanced degree or is female?

A)1/20
B)1/10
C)1/5
D)2/5
E)3/4

I did it this way- P(Advanced degree) OR P(Female)
(100/400)+(100/400) =1/2

I have not been able to apply the Manhattan Concepts in this problem.Im finding probability difficult,please advice on going about it.

Thanks
Dddanny2006,
You have added the female employee who has additional degree i.e. 40 twice.

P(Female) = 100/400
P(Advanced degree other than female) = 60/400

100/400 + 60/400 = 2/5

Hence Answer is D

Hope it helps you.

Regards,
Uva.

_________________
Known is a drop Unknown is an Ocean

vipulgoyal Master | Next Rank: 500 Posts
Joined
25 Jul 2011
Posted:
468 messages
Followed by:
4 members
29
Thu Nov 21, 2013 8:21 pm
P(Ad digree or female) = P(Ad digree) + P (female) - P(Ad digree and female)
= 1/4 + 1/4 - 1/10 = 2/5

riz_gmat Junior | Next Rank: 30 Posts
Joined
26 Sep 2013
Posted:
20 messages
5
Thu Nov 21, 2013 8:37 pm
Hi GMATGuruNY

But Question here is what is the probability this employee has an advanced degree or is female?

ie, Probability of that employee having advanced degree or Probability of that employee being female.
Nowhere in the question, it is mentioned employee having advanced degree cannot be female! Then why do you consider probability of male employees alone with advanced degree ?

Uva@90 Master | Next Rank: 500 Posts
Joined
04 Jul 2013
Posted:
490 messages
Followed by:
5 members
83
Thu Nov 21, 2013 10:02 pm
riz_gmat wrote:
Hi GMATGuruNY

But Question here is what is the probability this employee has an advanced degree or is female?

ie, Probability of that employee having advanced degree or Probability of that employee being female.
Nowhere in the question, it is mentioned employee having advanced degree cannot be female! Then why do you consider probability of male employees alone with advanced degree ?
Hi Riz_gmat,
What you said is partially right.
what question stated is "probability this employee has an advanced degree or is female?"
what Mitch did is,
First he calculated the probability of Female
then he calculated the probability of Male with Advanced degree.
probability of Female it includes both Female with Advanced degree and without advanced degree.

So, it is enough to add the probability of Male with Advanced degree. We no need to add again the Female with advanced degree, since it has already been added.

Hope it helps you.

Regards,
Uva.

_________________
Known is a drop Unknown is an Ocean

### GMAT/MBA Expert

Jeff@TargetTestPrep GMAT Instructor
Joined
09 Apr 2015
Posted:
1013 messages
Followed by:
13 members
39
Thu Dec 07, 2017 6:31 am
dddanny2006 wrote:
In a certain corporation, there are 300 male employees and 100 female employees. It is known that 20% of the male employees have advanced degrees and 40% of the females have advanced degrees. If one of the 400 employees is chosen at random, what is the probability this employee has an advanced degree or is female?

A)1/20
B)1/10
C)1/5
D)2/5
E)3/4
We are given that there are 400 total employees - 100 female and 300 male. We are also given that 20% of the male employees have advanced degree and that 40% of the females have advanced degrees.

Thus,

0.2 x 300 = 60 males with advanced degrees

And

0.4 x 100 = 40 females with advanced degrees

We see that 100 total employees had an advanced degree.

Since there are females with advanced degrees we have to subtract out any overlap when determining the probability of selecting a female or an employee with an advanced degree.

P(female or advanced degree) = P(female) + P(advanced degree) - P(both)

P(female or advanced degree) = 100/400 + 100/400 - 40/400

P(female or advanced degree) = 160/400 = 16/40 = 2/5

_________________
Jeffrey Miller Head of GMAT Instruction

### Top First Responders*

1 GMATGuruNY 67 first replies
2 Rich.C@EMPOWERgma... 44 first replies
3 Brent@GMATPrepNow 40 first replies
4 Jay@ManhattanReview 25 first replies
5 Terry@ThePrinceto... 10 first replies
* Only counts replies to topics started in last 30 days
See More Top Beat The GMAT Members

### Most Active Experts

1 GMATGuruNY

The Princeton Review Teacher

132 posts
2 Rich.C@EMPOWERgma...

EMPOWERgmat

112 posts
3 Jeff@TargetTestPrep

Target Test Prep

95 posts
4 Scott@TargetTestPrep

Target Test Prep

92 posts
5 Max@Math Revolution

Math Revolution

91 posts
See More Top Beat The GMAT Experts