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

Redeem

college teacher surveyed

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Source: — Data Sufficiency |

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 16207
Joined: Mon Dec 08, 2008 6:26 pm
Location: Vancouver, BC
Thanked: 5254 times
Followed by:1268 members
GMAT Score:770

by Brent@GMATPrepNow » Mon Sep 14, 2015 10:24 am
Of the 1400 College teachers surveyed 42% said they considered engaging in research an essential goal. How many of the college teachers surveyed were women?

1. In the survey 36% of the men and 50% of the women said that they considered engaging in research an essential goal.
2. In the survey, 288 men said they considered engaging in research an essential goal.

OA A
Target question: How many women?

Let W = # of women
Let M = # of men

Given: W + M = 1400

Statement 1: In the survey 36% of the men and 50% of the women said that they considered engaging in research an essential goal.
0.36M + 0.50W = # of teachers who consider research essential.
Well, we're already told that 42% of all 1400 teachers consider research essential.
So, 0.36M + 0.50W = (0.42)(1400)

So we have W + M = 1400 and 0.36M + 0.50W = (0.42)(1400)
Since we could solve this system for M and W, we can definitely answer the target question with certainty.
This means that statement 1 is SUFFICIENT

Statement 2: In the survey, 288 men said they considered engaging in research an essential goal.
We don't know the number of men altogether, so we don't know the percentage of men who consider research essential. Plus, we don't know anything about the women.
Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT

Answer = A

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
Image
Top
User avatar
Elite Legendary Member
Posts: 3991
Joined: Fri Jul 24, 2015 2:28 am
Location: Las Vegas, USA
Thanked: 19 times
Followed by:37 members

by Max@Math Revolution » Thu Sep 17, 2015 8:18 am
Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem.
Remember equal number of variables and independent equations ensures a solution.

Of the 1,4000 college teachers surveyed, 42 percent said that they considered engaging in research an a essential goal. How many of the college tehachers surveyed were women?
1) In the survey, 36 percent of the men and 50 percent of the women said they considered engaging in research an essential goal
2) In the survey, 288 men said that they considered engaging in research an essential goal

Transforming the original condition and the question, we have the below 2by2 table that are common in GMAT test

[/img]

There are 4 variables (a,b,c,d), 2 equations (a+b+c+d=1,400, a+b=1,400*0.42) and thus we need 2 more equations to match the number of variables and equations.
In case of 1), there are 2 equations (b=(b+d)*0.36, a=(a+c)*0.5) therefore the condition is sufficient.
In case of 2), there is 1 equation (b=288) therefore the condition is not sufficient. Therefore the answer is A


Normally for cases where we need 2 more equations, such as original conditions with 2 variable, or 3 variables and 1 equation, or 4 variables and 2 equations, we have 1 equation each in both 1) and 2). Therefore C has a high chance of being the answer, which is why we attempt to solve the question using 1) and 2) together. Here, there is 70% chance that C is the answer, while E has 25% chance. These two are the key questions. In case of common mistake type 3,4, the answer may be from A, B or D but there is only 5% chance. Since C is most likely to be the answer according to DS definition, we solve the question assuming C would be our answer hence using ) and 2) together. (It saves us time). Obviously there may be cases where the answer is A, B, D or E.

Math Revolution : Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World's First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Unlimited Access to over 120 free video lessons - try it yourself (https://www.mathrevolution.com/gmat/lesson)
See our Youtube demo (https://www.youtube.com/watch?v=R_Fki3_2vO8)[/img]
Attachments
BTG DS anant03 college teacher surveyed (20150916).png
Top
Master | Next Rank: 500 Posts
Posts: 313
Joined: Tue Oct 13, 2015 7:01 am
Thanked: 2 times

by jain2016 » Wed May 04, 2016 8:49 am
Brent@GMATPrepNow wrote:
Of the 1400 College teachers surveyed 42% said they considered engaging in research an essential goal. How many of the college teachers surveyed were women?

1. In the survey 36% of the men and 50% of the women said that they considered engaging in research an essential goal.
2. In the survey, 288 men said they considered engaging in research an essential goal.

OA A
Target question: How many women?

Let W = # of women
Let M = # of men

Given: W + M = 1400

Statement 1: In the survey 36% of the men and 50% of the women said that they considered engaging in research an essential goal.
0.36M + 0.50W = # of teachers who consider research essential.
Well, we're already told that 42% of all 1400 teachers consider research essential.
So, 0.36M + 0.50W = (0.42)(1400)
Hi Brent ,

Just a quick question.

In statement 1 we are given that 36% of the Men and 50% of the women said that they considered engaging in research an essential goal, but how about rest 14%? In those 14% there might be a women, who don't consider engaging in research an essential goal. SO we didn't include those 14% why?

Please explain and correct me.

Many thanks in advance.

SJ
Top

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 16207
Joined: Mon Dec 08, 2008 6:26 pm
Location: Vancouver, BC
Thanked: 5254 times
Followed by:1268 members
GMAT Score:770

by Brent@GMATPrepNow » Wed May 04, 2016 9:10 am
jain2016 wrote: Hi Brent ,

Just a quick question.

In statement 1 we are given that 36% of the Men and 50% of the women said that they considered engaging in research an essential goal, but how about rest 14%? In those 14% there might be a women, who don't consider engaging in research an essential goal. SO we didn't include those 14% why?

Please explain and correct me.

Many thanks in advance.

SJ
There's no missing 14%. We can't just add 50% and 36% to get 86% and conclude that we're missing 14% of the people.
To show this, we could have a scenario in which 80% of men and 70% of women enjoy pizza. If we add the percentages here, we get more than 100% but we still have a valid scenario.

If 36% of the Men and 50% of the women said that they considered engaging in research an essential goal, then we can also conclude that 64% of men and 50% of women DO NOT consider engaging in research an essential goal.

Does that help?

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
Image
Top
Master | Next Rank: 500 Posts
Posts: 313
Joined: Tue Oct 13, 2015 7:01 am
Thanked: 2 times

by jain2016 » Wed May 04, 2016 8:46 pm
Hi Brent ,

Thank you sir, I got it.

Thanks,

SJ
Top
Post new topic Post Reply
• Page 1 of 1