Find all School-related info fast with the new School-Specific MBA Forum

 It is currently 25 May 2013, 11:49

# Each employee of a certain task force is either a manager or

Author Message
TAGS:
GMAT Club team member
Joined: 02 Sep 2009
Posts: 11634
Followers: 1802

Kudos [?]: 9611 [0], given: 829

Re: DS Weighted Average [#permalink]  17 Jan 2013, 04:28
kingston wrote:
In a work force, the employees are either managers or directors. What is the percentage of directors?
(1) the average salary for manager is $5,000 less than the total average salary. (2) the average salary for directors is$15,000 more than the total average salary.

c

Merging similar topics. Please refer to the solutions above.

_________________
 Kaplan GMAT Prep Discount Codes Knewton GMAT Discount Codes Manhattan GMAT Discount Codes
Senior Manager
Joined: 13 Aug 2012
Posts: 468
Followers: 12

Kudos [?]: 75 [0], given: 11

Re: Each employee.. [#permalink]  23 Jan 2013, 06:58
Bunuel wrote:
achan wrote:
Each employee of a certain task force is either a manager or a director. What percent of the employees on the task force are directors?
1) the average ( Arithemetic mean) salary of the managers on the task force is 5000 less than the average salary of all the employees on the task force.
2) the average ( Arithemetic mean) salary of the directors on the task force is 15000 greater than the average salary of all the employees on the task force.

S_a - Average salary of all employees
S_m - Average salary for manager
S_d - Average salary of directors
d - # of directors;
m - # of managers.
Question \frac{d}{m+d}=?

(1) S_m=S_a-5000 --> Not sufficient to calculate ratio.
(2) S_d=S_a+15000 --> Not sufficient to calculate ratio.

(1)+(2) S_a=\frac{S_m*m+S_d*d}{d+m} --> substitute S_m and S_d --> S_a=\frac{(S_a-5000)*m+(S_a+15000)*d}{d+m} --> S_a*d+S_a*m=S_a*m-5000*m+S_a*d+15000*d --> S_a*d and S_a*m cancel out --> m=3d --> \frac{d}{m+d}=\frac{d}{3d+d}=\frac{1}{4}. Sufficient.

Or for (1)+(2): if we say that the fraction of the directors is x (x=\frac{d}{d+m}) then the fraction of the managers will be (1-x) (1-x=\frac{m}{d+m}) --> S_a=x(S_a+15000)+(1-x)(S_a-5000) --> S_a=x*S_a+15000x+S_a-5000-x*S_a+5000x --> x=\frac{1}{4}.

Do you have more example of this question type?
Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 3114
Location: Pune, India
Followers: 573

Kudos [?]: 2020 [0], given: 92

Re: DS Weighted Average [#permalink]  24 Jan 2013, 04:48
kingston wrote:
In a work force, the employees are either managers or directors. What is the percentage of directors?
(1) the average salary for manager is $5,000 less than the total average salary. (2) the average salary for directors is$15,000 more than the total average salary.

c

This is actually a direct application of weighted averages. If you recall the scale method (explained here: http://www.veritasprep.com/blog/2011/03 ... -averages/ ), this is what the number line will look like

AVG-5000 _____________ AVG _________________________AVG+15000

Number of managers/Number of directors = [(AVG+15000) - AVG]/[AVG - (AVG - 5000)] = 3/1

Percentage of directors = 1/(1+3) = 1/4 = 25%
_________________

Karishma
Veritas Prep | GMAT Instructor
My Blog

Save 10% on Veritas Prep GMAT Courses And Admissions Consulting
Enroll now. Pay later. Take advantage of Veritas Prep's flexible payment plan options.

Veritas Prep Reviews

Senior Manager
Joined: 29 Mar 2012
Posts: 251
Location: India
GMAT 1: 640 Q50 V26
GMAT 2: 660 Q50 V28
GMAT 3: 730 Q50 V38
Followers: 10

Kudos [?]: 52 [0], given: 20

Re: Each employee of a certain task force is either a manager or [#permalink]  18 Feb 2013, 10:09
I would prefer method of allegations in this problem.
achan wrote:
Each employee of a certain task force is either a manager or a director. What percent of the employees on the task force are directors?

(1) the average ( Arithemetic mean) salary of the managers on the task force is 5000 less than the average salary of all the employees on the task force.
(2) the average ( Arithemetic mean) salary of the directors on the task force is 15000 greater than the average salary of all the employees on the task force.

Posted from GMAT ToolKit
_________________

My posts: Solving Inequalities, Solving Simultaneous equations, Divisibility Rules

My story: 640 What a blunder!

My page:

Re: Each employee of a certain task force is either a manager or   [#permalink] 18 Feb 2013, 10:09
Similar topics Replies Last post
Similar
Topics:
Each employee on a certain task force is either a manager or 8 22 Jul 2005, 23:07
Each employee on a certain task force is either a manager or 7 20 Nov 2005, 01:23
Each employee on a certain task force is either a manager or 1 07 May 2006, 18:19
Each employee on a certain task force is either a manager or 2 08 Apr 2007, 09:45
Each employee in a certain task force is either a manager or 4 22 Apr 2008, 00:37
Display posts from previous: Sort by