GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 10 Dec 2018, 16:15

### 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 December
PrevNext
SuMoTuWeThFrSa
2526272829301
2345678
9101112131415
16171819202122
23242526272829
303112345
Open Detailed Calendar
• ### Free lesson on number properties

December 10, 2018

December 10, 2018

10:00 PM PST

11:00 PM PST

Practice the one most important Quant section - Integer properties, and rapidly improve your skills.
• ### Free GMAT Prep Hour

December 11, 2018

December 11, 2018

09:00 PM EST

10:00 PM EST

Strategies and techniques for approaching featured GMAT topics. December 11 at 9 PM EST.

# A can complete the job in 2 hours and B can complete the sam

 new topic post reply Question banks Downloads My Bookmarks Reviews Important topics
Author Message
TAGS:

### Hide Tags

Director
Joined: 07 Jun 2004
Posts: 599
Location: PA
A can complete the job in 2 hours and B can complete the sam  [#permalink]

### Show Tags

Updated on: 26 Mar 2014, 10:59
11
00:00

Difficulty:

45% (medium)

Question Stats:

68% (02:13) correct 32% (02:05) wrong based on 234 sessions

### HideShow timer Statistics

A can complete the job in 2 hours and B can complete the same job in 3 hours. A works for 1 hour and then B joins and both complete the job. What fraction of the job did B complete

A. 1/5
B. 3/10
C. 1/2
D. 5/6
E. 8/9

_________________

If the Q jogged your mind do Kudos me : )

Originally posted by rxs0005 on 17 Mar 2011, 04:21.
Last edited by Bunuel on 26 Mar 2014, 10:59, edited 1 time in total.
Renamed the topic, edited the question and added the OA.
Retired Moderator
Joined: 20 Dec 2010
Posts: 1820
Re: Word problem Work  [#permalink]

### Show Tags

17 Mar 2011, 04:35
1
A's rate = 1/2 W/h
B's rate = 1/3 W/h

In 1 hour A finished 1/2 W.

Only half of the work is left to be completed.

Together A and B can finish 1 work in;
1/2+1/3=1/t
t = 6/5 hours

So; they would have finished (1/2)W in half the time;

6/5*1/2 = 6/10 =(3/5)hour

B does 1/3 W in 1 hour
So, in 3/5 hour => 3/5*1/3 = 1/5 Work

Ans: "A"
_________________
Retired Moderator
Joined: 16 Nov 2010
Posts: 1426
Location: United States (IN)
Concentration: Strategy, Technology
Re: Word problem Work  [#permalink]

### Show Tags

17 Mar 2011, 04:43
1
1
1/2 + 1/3 = 5/6

so together they complete in 6/5 hrs and in 3/5 hrs they do 1/2 of Job together.

1/2 of job is done by A already, so they do remaning 1/2 and take 3/5 hrs for it.

So if B does 1/3 of job in 1 hr

in 3/5 hrs he'll complete 3/5 * 1/3 = 1/5 of Job

_________________

Formula of Life -> Achievement/Potential = k * Happiness (where k is a constant)

GMAT Club Premium Membership - big benefits and savings

SVP
Joined: 06 Sep 2013
Posts: 1728
Concentration: Finance
Re: Word problem Work  [#permalink]

### Show Tags

26 Mar 2014, 10:39
A does have of the job alone so 1/2 remains. Both A and B together do 5/6 of a job in an hour hence to do 1/2 of the job they will take 3/5 of an hour. In this time B does 3/5*1/3 = 1/5 of the job

Hence A is the correct answer choice

Please let me know if anything remains unclear
Cheers
J
SVP
Status: The Best Or Nothing
Joined: 27 Dec 2012
Posts: 1826
Location: India
Concentration: General Management, Technology
WE: Information Technology (Computer Software)
Re: A can complete the job in 2 hours and B can complete the sam  [#permalink]

### Show Tags

13 Jan 2015, 20:05
................................ Rate .............. Time ................. Work

A ................................ $$\frac{1}{2}$$ ............... 2 ....................... 1

B .............................. $$\frac{1}{3}$$ .................. 3 ........................ 1

Work done by A alone in 1 hour $$= \frac{1}{2} * 1 = \frac{1}{2}$$

Pending work $$= 1 - \frac{1}{2} = \frac{1}{2}$$

Combined rate of A & B$$= \frac{1}{2} + \frac{1}{3} = \frac{5}{6}$$

Time required for A & B combine to complete the remaining work $$= \frac{\frac{1}{2}}{\frac{5}{6}} = \frac{3}{5}$$

Work done by B in the combined effort $$= \frac{1}{3} * \frac{3}{5} = \frac{1}{5}$$

_________________

Kindly press "+1 Kudos" to appreciate

EMPOWERgmat Instructor
Status: GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 13057
Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: Q170 V170
Re: A can complete the job in 2 hours and B can complete the sam  [#permalink]

### Show Tags

13 Jan 2015, 20:15
2
1
Hi All,

The answer choices to this question are really helpful in getting to the correct answer - they're "spread out" enough that we can avoid almost all of the math and solve this with some logic and a "comparison."

We're told that A can complete a job in 2 hours and B can complete a job in 3 hours.

Next, we're told that A works alone for 1 hour. This means that A complete 1/2 of the job before B even shows up, so only 1/2 of the job remains to be completed.

If A and B worked at the SAME rate, then each would do "half of the half" of the job that's left. In total, A would end up doing 3/4 and B would end up doing 1/4 of the job.

HOWEVER, A works FASTER than B (2 hrs to 3 hrs to complete the job, respectively), so A does MORE than "half of the half" of the job that's left. This means that A does MORE then 3/4 and B does LESS than 1/4. Looking at the answers, there's only one that is LESS THAN 1/4.

GMAT assassins aren't born, they're made,
Rich
_________________

760+: Learn What GMAT Assassins Do to Score at the Highest Levels
Contact Rich at: Rich.C@empowergmat.com

# Rich Cohen

Co-Founder & GMAT Assassin

Special Offer: Save \$75 + GMAT Club Tests Free
Official GMAT Exam Packs + 70 Pt. Improvement Guarantee
www.empowergmat.com/

*****Select EMPOWERgmat Courses now include ALL 6 Official GMAC CATs!*****

VP
Joined: 07 Dec 2014
Posts: 1128
A can complete the job in 2 hours and B can complete the sam  [#permalink]

### Show Tags

Updated on: 20 Mar 2017, 07:27
t=time for A and B to complete job
t/2+t/3=1/2 of job
t=3/5 hour
(3/5)(1/3)=3/15=1/5 of job done by B

Originally posted by gracie on 20 Nov 2015, 16:10.
Last edited by gracie on 20 Mar 2017, 07:27, edited 1 time in total.
Non-Human User
Joined: 09 Sep 2013
Posts: 9098
Re: A can complete the job in 2 hours and B can complete the sam  [#permalink]

### Show Tags

27 Jul 2018, 08:56
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.
_________________
Re: A can complete the job in 2 hours and B can complete the sam &nbs [#permalink] 27 Jul 2018, 08:56
Display posts from previous: Sort by

# A can complete the job in 2 hours and B can complete the sam

 new topic post reply Question banks Downloads My Bookmarks Reviews Important topics

 Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.