May 27 01:00 AM PDT  11:59 PM PDT All GMAT Club Tests are free and open on May 27th for Memorial Day! May 27 10:00 PM PDT  11:00 PM PDT Special savings are here for Magoosh GMAT Prep! Even better  save 20% on the plan of your choice, now through midnight on Tuesday, 5/27 May 30 10:00 PM PDT  11:00 PM PDT Application deadlines are just around the corner, so now’s the time to start studying for the GMAT! Start today and save 25% on your GMAT prep. Valid until May 30th. Jun 01 07:00 AM PDT  09:00 AM PDT Learn reading strategies that can help even nonvoracious reader to master GMAT RC Jun 02 07:00 AM PDT  09:00 AM PDT Get personalized insights and an accurate assessment of your current quant score to achieve your Target Quant Score.
Author 
Message 
TAGS:

Hide Tags

Intern
Joined: 02 Apr 2014
Posts: 3

Understanding Time & Work formula
[#permalink]
Show Tags
02 Apr 2014, 03:00
Let M=Men, D=Days, H=Hours, W=Work M ∝ W (M is directly proportional to W) D ∝ W H ∝ W MDH ∝ W MDH = kW MDH/W = k I know MDH represents Total Men hour work and W represents 1 unit of work. Then what does the ratio MDH/W represents.



Magoosh GMAT Instructor
Joined: 28 Dec 2011
Posts: 4485

Re: Understanding Time & Work formula
[#permalink]
Show Tags
02 Apr 2014, 11:47
22990atinesh wrote: Let M=Men, D=Days, H=Hours, W=Work M ∝ W (M is directly proportional to W) D ∝ W H ∝ W MDH ∝ W MDH = kW MDH/W = k I know MDH represents Total Men hour work and W represents 1 unit of work. Then what does the ratio MDH/W represents. Dear 22990atinesh, I'm happy to respond. First of all, I'll suggest that if you put the k on the other side of the equation, it will be much more sensible: kMDH = W So that k = W/(MDH) which would make it vaguely ratelike. Work per manhourdays, something like that. I will say, I don't think know this formula is going to help you on the GMAT. You do have to know the basic idea of work rate R, where A = RT (A is the amount of work done). The GMAT tends not to ask a lot of questions about the amount of work done when you change the number of men or number of machines, and I have absolutely never seen anything testing the details of hours per day vs. days worked. The GMAT is much more apt to ask about two (or more) different machines (or people) working at different rates; the GMAT loves questions of that form  A works at this rate, B works at that rate, what happens when the work together? etc. See this blog for a further discussion: http://magoosh.com/gmat/2012/gmatworkrateproblems/This formula you have, and worrying about the meaning of k, is not going to help you at all on the work questions that are most typical on the GMAT. Does all this make sense? Mike
_________________
Mike McGarry Magoosh Test PrepEducation is not the filling of a pail, but the lighting of a fire. — William Butler Yeats (1865 – 1939)



Intern
Joined: 02 Apr 2014
Posts: 3

Re: Understanding Time & Work formula
[#permalink]
Show Tags
02 Apr 2014, 21:17
mikemcgarry wrote: 22990atinesh wrote: Let M=Men, D=Days, H=Hours, W=Work M ∝ W (M is directly proportional to W) D ∝ W H ∝ W MDH ∝ W MDH = kW MDH/W = k I know MDH represents Total Men hour work and W represents 1 unit of work. Then what does the ratio MDH/W represents. Dear 22990atinesh, I'm happy to respond. First of all, I'll suggest that if you put the k on the other side of the equation, it will be much more sensible: kMDH = W So that k = W/(MDH) which would make it vaguely ratelike. Work per manhourdays, something like that. I will say, I don't think know this formula is going to help you on the GMAT. You do have to know the basic idea of work rate R, where A = RT (A is the amount of work done). The GMAT tends not to ask a lot of questions about the amount of work done when you change the number of men or number of machines, and I have absolutely never seen anything testing the details of hours per day vs. days worked. ..... Hello mikemcgarry thanx for your response, I'm not a GMAT Aspirant, I'm just clearing my basic doubts of some aptitude topics.



Intern
Joined: 19 May 2014
Posts: 30

Re: Understanding Time & Work formula
[#permalink]
Show Tags
Updated on: 22 May 2014, 12:26
Dear 22990atinesh It's good that you are curious to understand the realworld significance of mathematical formulas. Coming to your ques, \(k = \frac{MDH}{W}\) = \(\frac{Total manhours worked}{Total units of work done}\) = Manhours required per unit of work You can appreciate that this ratio will be useful for some companies. For example, let's say, a car company is debating whether to purchase a few automation machines or not. They may use this ratio in their decisionmaking. For example, assembling of 1 car may normally take 100 manhours (that is, k=100), but with the automation machines, it may take only 40 manhours (that is, k'= 40). This looks like an attractive proposition! Of course, the management will also consider other factors, like costs, in making their decision.
_________________
Please press Kudos if you were helped by my post!
Originally posted by JapinderKaur on 22 May 2014, 11:58.
Last edited by JapinderKaur on 22 May 2014, 12:26, edited 1 time in total.



Intern
Joined: 20 May 2014
Posts: 35
Location: India

Re: Understanding Time & Work formula
[#permalink]
Show Tags
22 May 2014, 12:21
Dear 22990atinesh, This MDH = k(constant) * W can be used to solve problems where 2 situations in terms of men, days and hours are given: \(\frac{M1 * D1 * H1}{M2 * D2 * H2} = \frac{W1}{W2}\) , For example, If 6 men working 5 days for 8 hours each can finish a task. How many men would be needed for 4 days for 6 hours each to finish half the task? Answer: \(\frac{M1 * D1 * H1}{M2 * D2 * H2} = \frac{W1}{W2}\) = \(\frac{6 * 5 * 8}{M2 * 4 * 6} = \frac{1}{0.5}\) Solving, we get M2 = 5 menRgds, Rajat
_________________
If you liked the post, please press the'Kudos' button on the left



Intern
Joined: 02 Apr 2014
Posts: 3

Re: Understanding Time & Work formula
[#permalink]
Show Tags
23 May 2014, 22:01
MavenQ wrote: Dear 22990atinesh
It's good that you are curious to understand the realworld significance of mathematical formulas.
Coming to your ques, \(k = \frac{MDH}{W}\) = \(\frac{Total manhours worked}{Total units of work done}\) = Manhours required per unit of work
You can appreciate that this ratio will be useful for some companies. For example, let's say, a car company is debating whether to purchase a few automation machines or not. They may use this ratio in their decisionmaking. For example, assembling of 1 car may normally take 100 manhours (that is, k=100), but with the automation machines, it may take only 40 manhours (that is, k'= 40). This looks like an attractive proposition! Of course, the management will also consider other factors, like costs, in making their decision. Thanx MavenQ, I think I get it .You are trying to say that total Man hour/unit work is constant i.e. MDH/W=k. for example we have given that 2 Men working 3 hours/day works for 4 days to complete a work (unit of work). Calculate how many days required by 1 man working 2 hours/day to complete the 1/2 of that work. Sol: As we know Man hour/unit work is constant. Hence \(\frac{M_1D_1H_1}{W_1}=\frac{M_2D_2H_2}{W_2}\) Now we can easily plug data in LHS of the above equation. But for RHS as we know, we have to calculate days required by 1 man working 2 hours/day to complete the 1/2 of that work. so we have to double the total Man hour in RHS i.e. \(\frac{2*4*3}{1}=\frac{2*(1*X*2)}{1}\) \(\frac{2*4*3}{1}=\frac{(1*X*2)}{1/2}\) \(X=6\) Correct If I did something wrong.



Intern
Joined: 21 Jul 2018
Posts: 2

Understanding Time & Work formula
[#permalink]
Show Tags
13 Sep 2018, 05:24
22990atinesh wrote: mikemcgarry wrote: 22990atinesh wrote: Let M=Men, D=Days, H=Hours, W=Work M ∝ W (M is directly proportional to W) D ∝ W H ∝ W MDH ∝ W MDH = kW MDH/W = k I know MDH represents Total Men hour work and W represents 1 unit of work. Then what does the ratio MDH/W represents. Dear 22990atinesh, I'm happy to respond. First of all, I'll suggest that if you put the k on the other side of the equation, it will be much more sensible: kMDH = W So that k = W/(MDH) which would make it vaguely ratelike. Work per manhourdays, something like that. I will say, I don't think know this formula is going to help you on the GMAT. You do have to know the basic idea of work rate R, where A = RT (A is the amount of work done). The GMAT tends not to ask a lot of questions about the amount of work done when you change the number of men or number of machines, and I have absolutely never seen anything testing the details of hours per day vs. days worked. ..... Hello mikemcgarry thanx for your response, I'm not a GMAT Aspirant, I'm just clearing my basic doubts of some aptitude topics. Hi Mike, mikemcgarryCould you explain how do we work this question : Computer hackers can scan and infect 10 computers in 5 hours.If this group of hackers want to scan and infect 20 computers in 8 hours ,how many new computer hackers do they need to recruit and join their team inorder to accomplish this task,assuming all hackers work at the same rate. How do we solve this GMAT question




Understanding Time & Work formula
[#permalink]
13 Sep 2018, 05:24






