Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.
Customized for You
we will pick new questions that match your level based on your Timer History
Track Your Progress
every week, we’ll send you an estimated GMAT score based on your performance
Practice Pays
we will pick new questions that match your level based on your Timer History
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
It appears that you are browsing the GMAT Club forum unregistered!
Signing up is free, quick, and confidential.
Join other 500,000 members and get the full benefits of GMAT Club
Registration gives you:
Tests
Take 11 tests and quizzes from GMAT Club and leading GMAT prep companies such as Manhattan GMAT,
Knewton, and others. All are free for GMAT Club members.
Applicant Stats
View detailed applicant stats such as GPA, GMAT score, work experience, location, application
status, and more
Books/Downloads
Download thousands of study notes,
question collections, GMAT Club’s
Grammar and Math books.
All are free!
Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:
If Dev works alone he will take 20 more hours to complete a [#permalink]
02 Feb 2010, 05:30
1
This post received KUDOS
14
This post was BOOKMARKED
00:00
A
B
C
D
E
Difficulty:
85% (hard)
Question Stats:
56% (03:25) correct
44% (02:40) wrong based on 339 sessions
If Dev works alone he will take 20 more hours to complete a task than if he worked with Tina to complete the task. If Tina works alone, she will take 5 more hours to complete the complete the task, then if she worked with Dev to complete the task? What is the ratio of the time taken by Dev to that taken by Tina if each of them worked alone to complete the task?
Re: Ratio of Time to complete task [#permalink]
02 Feb 2010, 08:32
9
This post received KUDOS
1
This post was BOOKMARKED
answer is B:
If Dev works alone he will take 20 more hours to complete a task than if he worked with Tina to complete the task. If Tina works alone, she will take 5 more hours to complete the complete the task, then if she worked with Dev to complete the task? What is the ratio of the time taken by Dev to that taken by Tina if each of them worked alone to complete the task?
Take the time necessary to complete the job by both Dev and Tina to be x. From the problem statement, time necessary to complete the job by Dev alone is: x+20 From the problem statement, time necessary to complete the job by Tina alone is: x+5
Rate of work when Dev and Tina work together: 1/x Rate of work when Dev works alone: 1/(20+x) Rate of work when Tina works alone: 1/(5+x)
The rate of work when Tina and Dev works together is equal to sum of the rates when Tina and Dev work alone:
1/x=1/(20+x)+ 1/(5+x) When simplified the equation becomes:
X^2=100
X can only be the positive as we talk about tome, so x=10
The necessary ratio is T(Dev)/T(Tina)=(x+20)/(x+5)=30/15=2:1
Re: If Dev works alone he will take 20 more hours to complete a [#permalink]
18 Jan 2013, 22:08
1
This post received KUDOS
1
This post was BOOKMARKED
jusjmkol740 wrote:
If Dev works alone he will take 20 more hours to complete a task than if he worked with Tina to complete the task. If Tina works alone, she will take 5 more hours to complete the complete the task, then if she worked with Dev to complete the task? What is the ratio of the time taken by Dev to that taken by Tina if each of them worked alone to complete the task?
A. 4 : 1 B. 2 : 1 C. 10 : 1 D. 3 : 1 E. 1 : 2
Solved it in a minute! Here's my solution:
Description of the formula used: If A and B complete a task in x days, then A alone takes=x+a days and B alone take x+b days Formula: x=\sqrt{ab}
Re: If Dev works alone he will take 20 more hours to complete a [#permalink]
18 Feb 2014, 05:43
jusjmkol740 wrote:
If Dev works alone he will take 20 more hours to complete a task than if he worked with Tina to complete the task. If Tina works alone, she will take 5 more hours to complete the complete the task, then if she worked with Dev to complete the task? What is the ratio of the time taken by Dev to that taken by Tina if each of them worked alone to complete the task?
A. 4 : 1 B. 2 : 1 C. 10 : 1 D. 3 : 1 E. 1 : 2
Is there any way to solve this problem in a time efficient way? Experts please advice
Re: If Dev works alone he will take 20 more hours to complete a [#permalink]
18 Feb 2014, 20:35
3
This post received KUDOS
Expert's post
4
This post was BOOKMARKED
jlgdr wrote:
jusjmkol740 wrote:
If Dev works alone he will take 20 more hours to complete a task than if he worked with Tina to complete the task. If Tina works alone, she will take 5 more hours to complete the complete the task, then if she worked with Dev to complete the task? What is the ratio of the time taken by Dev to that taken by Tina if each of them worked alone to complete the task?
A. 4 : 1 B. 2 : 1 C. 10 : 1 D. 3 : 1 E. 1 : 2
Is there any way to solve this problem in a time efficient way? Experts please advice
Cheers J
Let's say when they work together, they take t hrs to complete the work. Dev takes 20 hrs extra when working alone because Tina did not work for t hrs and that work Dev had to do. Ratio of time take by Dev/Tina to do the same work = 20/t Tina takes 5 hrs extra when working alone because Dev did not work with her for t hrs and hence his part of work, Tine did in 5 hrs. Ratio of time taken by Dev/Tina to do the same work = t/5 20/t = t/5 (The ratio of time taken by Dev and Tina for the same work will always be the same irrespective of the amount of work) t = 10 Ratio of time taken by Dev/Tina = 20:10 = 2:1 Answer (B) _________________
Re: If Dev works alone he will take 20 more hours to complete a [#permalink]
18 Mar 2014, 03:58
1
This post received KUDOS
Again the funda of Rate * Time = Work
Time (Both) = T
For Dev:
Rate (Both) =T
Rate * Time = Work Rate * T+20 = 1
Rate (Dev) = 1/(T+20)
For Tina:
Rate * Time = Work Rate * T+5 = 1
Rate (Tina) = 1/(T+5)
Combined Rates = 1/(T+20) + 1/(T+5) = 1/T
Solving for it we will get you will get T=10
We want to know what is Time(D)/Time(T)= (T+20)/(T+5)=2:1 _________________
Rgds, TGC! _____________________________________________________________________ I Assisted You => KUDOS Please _____________________________________________________________________________
Re: If Dev works alone he will take 20 more hours to complete a [#permalink]
28 Apr 2015, 14:29
Hello from the GMAT Club BumpBot!
Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).
Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email. _________________
If Dev works alone he will take 20 more hours to complete a [#permalink]
30 Nov 2015, 15:02
jlgdr wrote:
jusjmkol740 wrote:
If Dev works alone he will take 20 more hours to complete a task than if he worked with Tina to complete the task. If Tina works alone, she will take 5 more hours to complete the complete the task, then if she worked with Dev to complete the task? What is the ratio of the time taken by Dev to that taken by Tina if each of them worked alone to complete the task?
A. 4 : 1 B. 2 : 1 C. 10 : 1 D. 3 : 1 E. 1 : 2
Is there any way to solve this problem in a time efficient way? Experts please advice
Cheers J
J, equate the answer options with (t+20)/(t+5) 2/1=(t+20)/(t+5) t=10 30/15=2/1 gracie
Re: If Dev works alone he will take 20 more hours to complete a [#permalink]
13 Jan 2016, 18:16
time work together: x time dev = x+20 time tina = x+5
1/x+20 + 1/x+5 = 1/x x+20+x+5/(x+20)(x+5) = 1/x
2x+25/(x+20)(x+5) = 1/x cross multiply 2x^2 +25x = x^2 +5x+25x-100 rearrange: x^2 - 100 = 0 factor: (x+10)(x-10)=0 x=10 or x=-10, since we are talking about hours, -10 is not a solution, thus x=10. time for dev=10+20=30 time tina = 10+5=15
time dev/time tina = 30/15 = 2/1
gmatclubot
Re: If Dev works alone he will take 20 more hours to complete a
[#permalink]
13 Jan 2016, 18:16
As I’m halfway through my second year now, graduation is now rapidly approaching. I’ve neglected this blog in the last year, mainly because I felt I didn’...
Wow! MBA life is hectic indeed. Time flies by. It is hard to keep track of the time. Last week was high intense training Yeah, Finance, Accounting, Marketing, Economics...