It is currently 22 Nov 2017, 22:52

### GMAT Club Daily Prep

#### 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

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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# A can do a job in 12 hrs B can do a job in 6 hours. If A and B work fo

Author Message
TAGS:

### Hide Tags

Director
Joined: 07 Jun 2004
Posts: 610

Kudos [?]: 952 [0], given: 22

Location: PA
A can do a job in 12 hrs B can do a job in 6 hours. If A and B work fo [#permalink]

### Show Tags

18 Aug 2010, 09:35
1
This post was
BOOKMARKED
00:00

Difficulty:

(N/A)

Question Stats:

90% (01:03) correct 10% (01:21) wrong based on 21 sessions

### HideShow timer Statistics

A can do a job in 12 hrs B can do a job in 6 hours. If A and B work for 3 hours , how many hours will it take A to finsih the rest of the job
_________________

If the Q jogged your mind do Kudos me : )

Kudos [?]: 952 [0], given: 22

Senior Manager
Status: Time to step up the tempo
Joined: 24 Jun 2010
Posts: 404

Kudos [?]: 259 [1], given: 50

Location: Milky way
Schools: ISB, Tepper - CMU, Chicago Booth, LSB
Re: A can do a job in 12 hrs B can do a job in 6 hours. If A and B work fo [#permalink]

### Show Tags

18 Aug 2010, 09:49
1
KUDOS
rxs0005 wrote:
A can do a job in 12 hrs B can do a job in 6 hours. If A and B work for 3 hours , how many hours will it take A to finsih the rest of the job

Answer: A would finish the job in 3 hours time.

In 3 hours, A would complete 1/4th of the job and B would complete 1/2 of the job.

Hence total job completed in 3 hours is 3/4th.

Rest 1/4 would be completed by A in 3 hours.
_________________

Support GMAT Club by putting a GMAT Club badge on your blog

Kudos [?]: 259 [1], given: 50

Non-Human User
Joined: 09 Sep 2013
Posts: 15546

Kudos [?]: 283 [0], given: 0

Re: A can do a job in 12 hrs B can do a job in 6 hours. If A and B work fo [#permalink]

### Show Tags

22 Aug 2017, 07:39
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.
_________________

Kudos [?]: 283 [0], given: 0

Director
Joined: 22 May 2016
Posts: 999

Kudos [?]: 347 [0], given: 594

A can do a job in 12 hrs B can do a job in 6 hours. If A and B work fo [#permalink]

### Show Tags

22 Aug 2017, 08:16
rxs0005 wrote:
A can do a job in 12 hrs B can do a job in 6 hours. If A and B work for 3 hours , how many hours will it take A to finsih the rest of the job

A's rate is $$\frac{1job}{12hrs}$$

B's rate is $$\frac{1job}{6hrs}$$

They work together for three hours; add their rates.

$$\frac{1}{12}$$ + $$\frac{1}{6}$$ = $$\frac{1}{4}$$

$$rt=W$$ is the work they will finish in 3 hours:

$$\frac{1}{4}$$* 3 = $$\frac{3}{4}$$ of the job (work) is finished.

A will finish the remaining $$\frac{1}{4}$$W in $$W/r= t$$:

$$\frac{\frac{1}{4}}{\frac{1}{12}}$$ = 3 hours for A to finish the rest of the work

Kudos [?]: 347 [0], given: 594

Board of Directors
Status: QA & VA Forum Moderator
Joined: 11 Jun 2011
Posts: 3102

Kudos [?]: 1117 [0], given: 327

Location: India
GPA: 3.5
Re: A can do a job in 12 hrs B can do a job in 6 hours. If A and B work fo [#permalink]

### Show Tags

22 Aug 2017, 08:45
rxs0005 wrote:
A can do a job in 12 hrs B can do a job in 6 hours. If A and B work for 3 hours , how many hours will it take A to finsih the rest of the job

Let the total work be 12 units

Efficiency of A = 1 unit/hr
Efficiency of B = 2 unit/hr

Combined Efficiency of A & B = 3 unit/hr

Quote:
If A and B work for 3 hours

Work completed is 3*3 = 9 units , work remaining is 3 units.

So, A will complete the remaining work in 3 hours.
_________________

Thanks and Regards

Abhishek....

PLEASE FOLLOW THE RULES FOR POSTING IN QA AND VA FORUM AND USE SEARCH FUNCTION BEFORE POSTING NEW QUESTIONS

How to use Search Function in GMAT Club | Rules for Posting in QA forum | Writing Mathematical Formulas |Rules for Posting in VA forum | Request Expert's Reply ( VA Forum Only )

Kudos [?]: 1117 [0], given: 327

Intern
Joined: 21 Aug 2017
Posts: 2

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

Re: A can do a job in 12 hrs B can do a job in 6 hours. If A and B work fo [#permalink]

### Show Tags

23 Aug 2017, 00:45
All the solutions appear to me as \\ frac {1} like this type it is not clearly legible what to do

Sent from my XT1022 using GMAT Club Forum mobile app

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

Math Expert
Joined: 02 Sep 2009
Posts: 42305

Kudos [?]: 133079 [0], given: 12403

Re: A can do a job in 12 hrs B can do a job in 6 hours. If A and B work fo [#permalink]

### Show Tags

23 Aug 2017, 00:54
subham0001 wrote:
All the solutions appear to me as \\ frac {1} like this type it is not clearly legible what to do

Sent from my XT1022 using GMAT Club Forum mobile app

_________________

Kudos [?]: 133079 [0], given: 12403

Target Test Prep Representative
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 1821

Kudos [?]: 942 [0], given: 3

Location: United States (CA)
Re: A can do a job in 12 hrs B can do a job in 6 hours. If A and B work fo [#permalink]

### Show Tags

24 Aug 2017, 16:06
rxs0005 wrote:
A can do a job in 12 hrs B can do a job in 6 hours. If A and B work for 3 hours , how many hours will it take A to finsih the rest of the job

We can let the rate of A = 1/12, the rate of B = 1/6, the time of A = t + 3 (where t is the number of hours it takes A to finish the rest of the job), and the time of B = 3. Thus:

(1/12)(t + 3) + (1/6)3 = 1

(t + 3)/12 + 1/2 = 1

(t + 3)/12 = 1/2

Multiplying by 12, we have:

t + 3 = 6

t = 3
_________________

Scott Woodbury-Stewart
Founder and CEO

GMAT Quant Self-Study Course
500+ lessons 3000+ practice problems 800+ HD solutions

Kudos [?]: 942 [0], given: 3

Manager
Joined: 17 Feb 2017
Posts: 64

Kudos [?]: 47 [2], given: 42

Location: India
GMAT 1: 720 Q49 V40
GPA: 3.69
A can do a job in 12 hrs B can do a job in 6 hours. If A and B work fo [#permalink]

### Show Tags

27 Aug 2017, 03:16
2
KUDOS
guys today i will show you a way to solve word problems which avoids fractions and tedious calculations which can help you solve hard complex problems in 90 secs. I have used it in gmat and it saved me a lot of time

for this sum
assume the job as 24 ( this number can be any lcm of the time take)
rate for a =24/12
= 2 units/hr
rate for b = 24/6
= 4 units/hr
if a and b work for 3 hrs together rate is 2+4=6
work done is 6*3=18 units
work left is 24-18=6 units
time taken by a to finish the job is 6/2=3

this approach can be applied to any sum of work rate . it gives fast results only assumption is the unit of work. For a sum to fill water in a tank you assume the capacity of tank

Kudos [?]: 47 [2], given: 42

Intern
Joined: 21 Aug 2017
Posts: 2

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

Re: A can do a job in 12 hrs B can do a job in 6 hours. If A and B work fo [#permalink]

### Show Tags

16 Nov 2017, 23:02
Bunuel wrote:
subham0001 wrote:
All the solutions appear to me as \\ frac {1} like this type it is not clearly legible what to do

Sent from my XT1022 using GMAT Club Forum mobile app

I am using the app but on browser its okay.

Sent from my XT1022 using GMAT Club Forum mobile app

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

Re: A can do a job in 12 hrs B can do a job in 6 hours. If A and B work fo   [#permalink] 16 Nov 2017, 23:02
Display posts from previous: Sort by