BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Conflicting DS statements - Quant Edition 2 Q92

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Legendary Member
Posts: 768
Joined: Mon Nov 30, 2009 3:46 am
Thanked: 21 times
Followed by:7 members

Conflicting DS statements - Quant Edition 2 Q92

by GMATMadeEasy » Thu Jun 30, 2011 10:54 am
In a certain office, 50 percent of the employees are college graduates and 60 percent of the employees are over 40 years old. If 30 percent of those over 40 have master's degrees, how many of the employees
over forty have master's degrees?

(1) Exactly 100 of the employees are college graduates.
(2) Of the employees forty years old or less, 25 percent have master's degrees

From question stem we can conclude that there are 32% of people in under 40 and master degree group whereas second statement says that "Of the employees forty years old or less, 25 percent have master's degrees" that makes it 10 percent.
Top
Source: — Data Sufficiency |

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 2623
Joined: Mon Jun 02, 2008 3:17 am
Location: Montreal
Thanked: 1090 times
Followed by:355 members
GMAT Score:780

by Ian Stewart » Thu Jun 30, 2011 11:59 am
GMATMadeEasy wrote:In a certain office, 50 percent of the employees are college graduates and 60 percent of the employees are over 40 years old. If 30 percent of those over 40 have master's degrees, how many of the employees
over forty have master's degrees?

(1) Exactly 100 of the employees are college graduates.
(2) Of the employees forty years old or less, 25 percent have master's degrees

From question stem we can conclude that there are 32% of people in under 40 and master degree group whereas second statement says that "Of the employees forty years old or less, 25 percent have master's degrees" that makes it 10 percent.
You won't find a single example of a question with conflicting statements in either Official Guide; if you think you've found such a question, you've made some kind of mistake. I don't know how you arrived at the '32%' figure, but it is not right; there is nothing in the stem alone that lets you determine what percentage of employees are under 40 and have Master's degrees. We know:

60% of employees are over 40
* 18% of employees are both over 40 and have Master's degrees (since 30% of employees over 40 have Master's degrees)
* 42% of employees are over 40 and do not have Master's degrees
40% of employees are under 40
* 10% of employees are under 40 and have Master's degrees (if you use Statement 2)
* 30% of employees are under 40 and do not have Master's degrees (using Statement 2)

Further we know that half of all employees are college graduates. There's nothing conflicting about the information here.

Since the question asks for a number, we need some kind of number (not just a percentage) to answer the question. From Statement 1 alone we know that there are 200 employees in total, which we can use to answer the question.
For online GMAT math tutoring, or to buy my higher-level Quant books and problem sets, contact me at ianstewartgmat at gmail.com

ianstewartgmat.com
Top
Legendary Member
Posts: 768
Joined: Mon Nov 30, 2009 3:46 am
Thanked: 21 times
Followed by:7 members

by GMATMadeEasy » Thu Jun 30, 2011 12:43 pm
Yeah, I might be doing wrong but I could not track it. Here is how i calculated . Let me know I might have made a mistake.

From your post :
------------
60% of employees are over 40
* 18% of employees are both over 40 and have Master's degrees (since 30% of employees over 40 have Master's degrees)
* 42% of employees are over 40 and do not have Master's degrees
40% of employees are under 40
--------------
now, if we arrange it in double set matrix :
From question stem
50 percent of the employees are college graduates (DO NOT have master degree)
* Since 42% of employees are over 40 and do not have Master's degrees, 8 percent are over 40 and DO NOT have master degree. (simple college graduates)
We will also say that
50 percent of the employees have master degree

Since 18% of employees are both over 40 and have Master's degrees, 32 percent are less than 40 and have master degree.

----------
Top

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 2623
Joined: Mon Jun 02, 2008 3:17 am
Location: Montreal
Thanked: 1090 times
Followed by:355 members
GMAT Score:780

by Ian Stewart » Thu Jun 30, 2011 1:01 pm
GMATMadeEasy wrote:
now, if we arrange it in double set matrix :
From question stem
50 percent of the employees are college graduates (DO NOT have master degree)
* Since 42% of employees are over 40 and do not have Master's degrees, 8 percent are over 40 and DO NOT have master degree. (simple college graduates)
We will also say that
50 percent of the employees have master degree

Since 18% of employees are both over 40 and have Master's degrees, 32 percent are less than 40 and have master degree.
I've highlighted the two parts of your reasoning that I don't follow. In the red portion, you say that '42% of employees are over 40 and do not have Master's degrees' and from that conclude that "8 percent are over 40 and DO NOT have master degree." We've just established that 42% are in this category, not 8%.

Because I can't follow your reasoning, it's difficult for me to pinpoint your error, but I think you might be confusing the category 'college graduates' with 'have Master's degrees'. One can be a college graduate without having a Master's degree. I think you also may be assuming that 50% of all people over 40 are college graduates, and we have no information about the ages of college graduates here, so we cannot assume that 50% of people over 40 are (or are not) college graduates, and similarly cannot conclude that 50% of people under 40 are (or are not) college graduates.
For online GMAT math tutoring, or to buy my higher-level Quant books and problem sets, contact me at ianstewartgmat at gmail.com

ianstewartgmat.com
Top
Legendary Member
Posts: 768
Joined: Mon Nov 30, 2009 3:46 am
Thanked: 21 times
Followed by:7 members

by GMATMadeEasy » Thu Jun 30, 2011 1:48 pm
surely, something is going wrong somewhere. The first thing to clarify whether we can divide the group into With Master degree and NOT master degree (that is college graduate )

sample double set

College graduate Master Degree

Over 40 42% 18% 60%

Less 40 8% 32% 40%
-----------------------------------------------
50 50 100%

My assumptions:
1. If 50 percent of the employees are college graduates(not masters) then rest 50% are having master degree.
Top

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 2623
Joined: Mon Jun 02, 2008 3:17 am
Location: Montreal
Thanked: 1090 times
Followed by:355 members
GMAT Score:780

by Ian Stewart » Thu Jun 30, 2011 2:56 pm
GMATMadeEasy wrote:
My assumptions:
1. If 50 percent of the employees are college graduates(not masters) then rest 50% are having master degree.
Oh I see now what you were doing. It's this assumption which is wrong. Some employees might never have gone to college, some employees might have only an undergraduate degree, and some employees may have a Master's degree. The 50% who are college graduates *includes* the people who have Master's degrees (since you have to graduate from college to get a Master's degree) but also includes other people who only have undergraduate degrees. The people with college degrees are certainly not a separate group from those with Master's degrees, as you've assumed.
For online GMAT math tutoring, or to buy my higher-level Quant books and problem sets, contact me at ianstewartgmat at gmail.com

ianstewartgmat.com
Top
Post new topic Post Reply
• Page 1 of 1