Al can complete a particular job in 8 hours. Boris can : GMAT Problem Solving (PS)
Check GMAT Club App Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

 It is currently 10 Dec 2016, 05:29

### 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

# Al can complete a particular job in 8 hours. Boris can

Author Message
TAGS:

### Hide Tags

Manager
Joined: 25 May 2006
Posts: 227
Followers: 1

Kudos [?]: 57 [3] , given: 0

Al can complete a particular job in 8 hours. Boris can [#permalink]

### Show Tags

11 Jul 2006, 20:20
3
KUDOS
19
This post was
BOOKMARKED
00:00

Difficulty:

75% (hard)

Question Stats:

66% (03:25) correct 34% (02:57) wrong based on 465 sessions

### HideShow timer Statistics

Al can complete a particular job in 8 hours. Boris can complete the same job in 5 hours. Cody can complete a second job, which requires twice as much work as the first, in 8 hours. If all three people work together on the larger job for 2 hours, how long, in hours, would it take Al, working alone, to finish the job?

A. 0.8
B. 3.0
C. 6.8
D. 8.0
E. 8.8
[Reveal] Spoiler: OA

_________________

Who is John Galt?

Director
Joined: 09 Oct 2005
Posts: 720
Followers: 3

Kudos [?]: 23 [2] , given: 0

### Show Tags

11 Jul 2006, 20:43
2
KUDOS
X & Y wrote:
Al can complete a particular job in 8 hours. Boris can complete the same job in 5 hours. Cody can complete a second job, which requires twice as much work as the first, in 8 hours. If all three people work together on the larger job for 2 hours, how long, in hours, would it take Al, working alone, to finish the job?

a. 0.8
b. 3.0
c. 6.8
d. 8.0
e. 8.8

all three people working together on the larger job for 2 hours=(1/16+1/10+1/8)*2=23/40
remaining part of the job is 17/40 Al's working rate is 1/16 hence
(17/40)/(1/16)=34/5 or 6.8 C it is
_________________

IE IMBA 2010

Senior Manager
Joined: 30 Aug 2009
Posts: 286
Location: India
Concentration: General Management
Followers: 3

Kudos [?]: 156 [1] , given: 5

### Show Tags

03 Dec 2009, 22:49
1
KUDOS
ro86 wrote:
Al can complete a particular job in 8 hours. Boris can complete the same job in 5. Cody can complete a second job, which requires twice as much work as the first, in 8 hours. If all three people work together on the larger job for 2 hours. How long, in hours, would it take Al, working alone to finish the job?

1. 0.8
2. 3.0
3. 6.8
4. 8.0
5. 8.8
I am confused as to how to evaluate the 2nd statement "Cody can complete a second job, which requires twice as much work as the first, in 8 hours"

the statement means if A and B are doing work "W" then Cody does a work which is "2W"
Now considering they work at the same workrate A will take 16hrs and B will take 10hrs to do the second job.
In 2hrs A,B and C will complete 2/16 + 2/10 + 2/8 = 92/160 part of the work
remaining work is 1-92/160 = 68/160
A does 1/16 part of second job in 1hr so he would require (68/160)/(1/16) = 6.8hrs
Manager
Joined: 22 Jan 2012
Posts: 90
Location: India
Concentration: General Management, Technology
GMAT 1: Q39 V29
GPA: 3.3
WE: Engineering (Consulting)
Followers: 6

Kudos [?]: 98 [5] , given: 9

Re: Al can complete a particular job in 8 hours. Boris can [#permalink]

### Show Tags

19 Mar 2012, 19:28
5
KUDOS
1
This post was
BOOKMARKED
Al's rate for smaller job = 1/8
Bigger job = 1/16

Boris rate for smaller job = 1/5
bigger job = 1/10

Cody's rate = 1/8

Work together for 2 hours on larger job

rate * time = work

(1/16+1/10+1/8) * 2 = work

work = 23/40

17/40 of the works remains

If Al was to work by himself to complete this then again

rate * time = work

1/16*time = 17/40

time = 6.8
_________________

Press +1 Kudos rather than saying thanks

Ill be posting good questions as many as I can...

Towards Success

Manager
Joined: 12 Feb 2012
Posts: 136
Followers: 1

Kudos [?]: 48 [0], given: 28

Re: Al can complete a particular job in 8 hours. Boris can [#permalink]

### Show Tags

05 May 2012, 06:38
I am stumped by this question.

Al's rate is 1 Job / 8 Hours
Boris's rate is 1 Job/ 5 Hours
Cody's rate is 2 Job /8 Hours

When the question states that the second job required "twice the amount of work as the first" how does one interpret this? In the above posts you have the the time doubled, ie, Al's rate is no longer 1/8 but 1/16 (so the time to complete the job was doubled). But I saw it more as his rate to complete the job stayed the same and the job grew by a multiple of 2, ie, (1/8)*time_Al=2 job
The rate should be doubled in the numerator and the denominator.So Al's rate of 1 Job/8 Hour becomes (2*1 Job/2*8 Hour)=2 Job/16 Hour
Very confused.
Math Expert
Joined: 02 Sep 2009
Posts: 35945
Followers: 6862

Kudos [?]: 90109 [2] , given: 10417

Re: Al can complete a particular job in 8 hours. Boris can [#permalink]

### Show Tags

06 May 2012, 02:16
2
KUDOS
Expert's post
2
This post was
BOOKMARKED
alphabeta1234 wrote:
I am stumped by this question.

Al's rate is 1 Job / 8 Hours
Boris's rate is 1 Job/ 5 Hours
Cody's rate is 2 Job /8 Hours

When the question states that the second job required "twice the amount of work as the first" how does one interpret this? In the above posts you have the the time doubled, ie, Al's rate is no longer 1/8 but 1/16 (so the time to complete the job was doubled). But I saw it more as his rate to complete the job stayed the same and the job grew by a multiple of 2, ie, (1/8)*time_Al=2 job
The rate should be doubled in the numerator and the denominator.So Al's rate of 1 Job/8 Hour becomes (2*1 Job/2*8 Hour)=2 Job/16 Hour
Very confused.

Al can complete a particular job in 8 hours. Boris can complete the same job in 5 hours. Cody can complete a second job, which requires twice as much work as the first, in 8 hours. If all three people work together on the larger job for 2 hours, how long, in hours, would it take Al, working alone, to finish the job?
A. 0.8
B. 3.0
C. 6.8
D. 8.0
E. 8.8

Al can complete a particular job in 8 hours, hence he can complete the second job which requires twice as much work as the first in 16 hours --> the rate of Al for this larger job is 1/16 job/hour;

Boris can complete a particular job in 5 hours, hence he can complete the second job which requires twice as much work as the first in 10 hours --> the rate of Boris for this larger job is 1/10 job/hour;

The rate of Cody for this larger job is 1/8 job/hour.

In 2 hours all three would complete 2*(1/16+1/10+1/8)=23/40 part of the larger job, so 17/40 part of it is left to be done.

Al can complete it in time=job/rate=(17/40)/(1/16)=34/5=6.8 hours.

Hope it's clear.
_________________
Intern
Joined: 03 Apr 2012
Posts: 27
Followers: 0

Kudos [?]: 9 [0], given: 10

Re: Al can complete a particular job in 8 hours. Boris can [#permalink]

### Show Tags

07 May 2012, 17:39
Bunuel wrote:
alphabeta1234 wrote:
I am stumped by this question.

Al's rate is 1 Job / 8 Hours
Boris's rate is 1 Job/ 5 Hours
Cody's rate is 2 Job /8 Hours

When the question states that the second job required "twice the amount of work as the first" how does one interpret this? In the above posts you have the the time doubled, ie, Al's rate is no longer 1/8 but 1/16 (so the time to complete the job was doubled). But I saw it more as his rate to complete the job stayed the same and the job grew by a multiple of 2, ie, (1/8)*time_Al=2 job
The rate should be doubled in the numerator and the denominator.So Al's rate of 1 Job/8 Hour becomes (2*1 Job/2*8 Hour)=2 Job/16 Hour
Very confused.

Al can complete a particular job in 8 hours. Boris can complete the same job in 5 hours. Cody can complete a second job, which requires twice as much work as the first, in 8 hours. If all three people work together on the larger job for 2 hours, how long, in hours, would it take Al, working alone, to finish the job?
A. 0.8
B. 3.0
C. 6.8
D. 8.0
E. 8.8

Al can complete a particular job in 8 hours, hence he can complete the second job which requires twice as much work as the first in 16 hours --> the rate of Al for this larger job is 1/16 job/hour;

Boris can complete a particular job in 5 hours, hence he can complete the second job which requires twice as much work as the first in 10 hours --> the rate of Boris for this larger job is 1/10 job/hour;

The rate of Cody for this larger job is 1/8 job/hour.

In 2 hours all three would complete 2*(1/16+1/10+1/8)=23/40 part of the larger job, so 17/40 part of it is left to be done.

Al can complete it in time=job/rate=(17/40)/(1/16)=34/5=6.8 hours.

Hope it's clear.

I understand the solution, but i have to question the structure of the sentence "which requires twice as much work as the first". it is assumed that Al and Boris too takes twice the amount of time and that double time is not applicable solely to Cody.
Math Expert
Joined: 02 Sep 2009
Posts: 35945
Followers: 6862

Kudos [?]: 90109 [0], given: 10417

Re: Al can complete a particular job in 8 hours. Boris can [#permalink]

### Show Tags

08 May 2012, 00:09
Bunuel wrote:
alphabeta1234 wrote:
I am stumped by this question.

Al's rate is 1 Job / 8 Hours
Boris's rate is 1 Job/ 5 Hours
Cody's rate is 2 Job /8 Hours

When the question states that the second job required "twice the amount of work as the first" how does one interpret this? In the above posts you have the the time doubled, ie, Al's rate is no longer 1/8 but 1/16 (so the time to complete the job was doubled). But I saw it more as his rate to complete the job stayed the same and the job grew by a multiple of 2, ie, (1/8)*time_Al=2 job
The rate should be doubled in the numerator and the denominator.So Al's rate of 1 Job/8 Hour becomes (2*1 Job/2*8 Hour)=2 Job/16 Hour
Very confused.

Al can complete a particular job in 8 hours. Boris can complete the same job in 5 hours. Cody can complete a second job, which requires twice as much work as the first, in 8 hours. If all three people work together on the larger job for 2 hours, how long, in hours, would it take Al, working alone, to finish the job?
A. 0.8
B. 3.0
C. 6.8
D. 8.0
E. 8.8

Al can complete a particular job in 8 hours, hence he can complete the second job which requires twice as much work as the first in 16 hours --> the rate of Al for this larger job is 1/16 job/hour;

Boris can complete a particular job in 5 hours, hence he can complete the second job which requires twice as much work as the first in 10 hours --> the rate of Boris for this larger job is 1/10 job/hour;

The rate of Cody for this larger job is 1/8 job/hour.

In 2 hours all three would complete 2*(1/16+1/10+1/8)=23/40 part of the larger job, so 17/40 part of it is left to be done.

Al can complete it in time=job/rate=(17/40)/(1/16)=34/5=6.8 hours.

Hope it's clear.

I understand the solution, but i have to question the structure of the sentence "which requires twice as much work as the first". it is assumed that Al and Boris too takes twice the amount of time and that double time is not applicable solely to Cody.

Yes. We are told that "a second job, ... requires twice as much work as the first", so it's not only for Coby but for everyone.
_________________
Manager
Joined: 26 Dec 2011
Posts: 117
Followers: 1

Kudos [?]: 32 [0], given: 17

Re: Al can complete a particular job in 8 hours. Boris can [#permalink]

### Show Tags

10 May 2012, 05:05
I did another way, may be it is helpful.

Assume the work is W

as per the conditions: rate of Al: W/8; rate of Boris w/5 and rate of Cody 2w/8

they work together for 2 hours: 2w/8 + 2w/5 + 4w/8 = 46w/40; remaining work from the larger = 2w-46w/40 = 34w/40

thus. time * w/8 = 34w/40 ... time = 6.8
Manager
Joined: 25 Jun 2012
Posts: 71
Location: India
WE: General Management (Energy and Utilities)
Followers: 4

Kudos [?]: 103 [0], given: 15

Re: Al can complete a particular job in 8 hours. Boris can [#permalink]

### Show Tags

21 Sep 2012, 05:06
Al can complete a particular job in 8 hours. Boris can complete the same job in 5 hours. Cody can complete a second job, which requires twice as much work as the first, in 8 hours. If all three people work together on the larger job for 2 hours, how long, in hours, would it take Al, working alone, to finish the job?

Bunuel ,question stem does not mention to find time for Al to complete remaining job.
I misunderstood the question and calculated time for Al to finish the whole job.
Math Expert
Joined: 02 Sep 2009
Posts: 35945
Followers: 6862

Kudos [?]: 90109 [0], given: 10417

Re: Al can complete a particular job in 8 hours. Boris can [#permalink]

### Show Tags

21 Sep 2012, 05:22
bhavinshah5685 wrote:
Al can complete a particular job in 8 hours. Boris can complete the same job in 5 hours. Cody can complete a second job, which requires twice as much work as the first, in 8 hours. If all three people work together on the larger job for 2 hours, how long, in hours, would it take Al, working alone, to finish the job?

Bunuel ,question stem does not mention to find time for Al to complete remaining job.
I misunderstood the question and calculated time for Al to finish the whole job.

I understand your point and agree that wording could have been better. Though notice that we are asked "how long, in hours, would it take Al, working alone, to finish the job?"
_________________
Intern
Joined: 05 Mar 2014
Posts: 9
Schools: Ross '18
Followers: 0

Kudos [?]: 0 [0], given: 275

Re: Al can complete a particular job in 8 hours. Boris can [#permalink]

### Show Tags

29 Mar 2014, 15:04

A rate = 1/8 (smaller job) or 1/16 (longer job)

B rate = 1/5 (smaller job) or 1/10 (longer job)

C rate = 1/4 (smaller job) or 1/8 (longer job)

((1/16)+(1/10)+(1/8))*2(hours) = 23/40 (work done in 2 hours) so rests for A, 17/40 to finish or 34/80.

A has a rate of 1/16 or 5/80. 34/5 = 6,8

SVP
Status: The Best Or Nothing
Joined: 27 Dec 2012
Posts: 1858
Location: India
Concentration: General Management, Technology
WE: Information Technology (Computer Software)
Followers: 44

Kudos [?]: 1837 [0], given: 193

Re: Al can complete a particular job in 8 hours. Boris can [#permalink]

### Show Tags

30 Oct 2014, 00:16
Al's rate for large Job $$= \frac{1}{8} *\frac{1}{2} = \frac{1}{16}$$

Boris rate for Large Job $$= \frac{1}{5} * \frac{1}{2} = \frac{1}{10}$$

Cody's rate for large Job $$= \frac{1}{8}$$

Combined rate for Large Job$$= \frac{1}{8} + \frac{1}{10} + \frac{1}{16} = \frac{23}{80}$$

Work done (combined) in 2 hrs$$= \frac{23}{40} * 2 = \frac{23}{40}$$

Remaining work $$= 1- \frac{23}{40} = \frac{17}{40}$$

Time * Al's rate$$= \frac{17}{40}$$

Time required by Al$$= \frac{17}{40} * 16 = 6.8$$

Bunuel: Kindly update OA .......
_________________

Kindly press "+1 Kudos" to appreciate

SVP
Joined: 17 Jul 2014
Posts: 2091
Location: United States (IL)
Concentration: Finance, Economics
Schools: Stanford '19
GMAT 1: 550 Q39 V27
GMAT 2: 560 Q42 V26
GMAT 3: 560 Q43 V24
GMAT 4: 650 Q49 V30
WE: General Management (Transportation)
Followers: 18

Kudos [?]: 248 [0], given: 124

Re: Al can complete a particular job in 8 hours. Boris can [#permalink]

### Show Tags

07 Dec 2015, 17:49
the wording of the question is terrible...
Manager
Joined: 03 Apr 2013
Posts: 117
Followers: 4

Kudos [?]: 17 [0], given: 526

Re: Al can complete a particular job in 8 hours. Boris can [#permalink]

### Show Tags

19 Jul 2016, 03:50
X & Y wrote:
Al can complete a particular job in 8 hours. Boris can complete the same job in 5 hours. Cody can complete a second job, which requires twice as much work as the first, in 8 hours. If all three people work together on the larger job for 2 hours, how long, in hours, would it take Al, working alone, to finish the job?

A. 0.8
B. 3.0
C. 6.8
D. 8.0
E. 8.8

Let the total(original) job be 40 units..larger is 80 units

Al's units per hour = 40/8 = 5 units
Similarly
Boris' = 8 units
Cody's = 10 units

in 2 hrs they together complete 46 units
Units left for the larger job = 80 - 46 = 34 units

Al's time for the rest of this job = 34/5 = 6.8(C)..

_________________

Spread some love..Like = +1 Kudos

Senior Manager
Status: Exam scheduled!!
Joined: 05 Sep 2016
Posts: 401
Location: United States (WI)
Concentration: Marketing, Technology
WE: Other (Law)
Followers: 3

Kudos [?]: 11 [0], given: 212

Re: Al can complete a particular job in 8 hours. Boris can [#permalink]

### Show Tags

15 Nov 2016, 18:56
Al --> 40 bricks = R x 8hrs --> R=5

Boris --> 40 bricks = R x 5hrs --> R=8

Cody --> 80 bricks = R x 8hrs --> R = 10

Al + Boris + Cody --> 2 hours spent together on larger job (aka 80 bricks)
20+10+16=46
80-46 = 34 bricks remain for Al to complete on his own

How long will it take Al?
W=RxT --> 34=5T --> 6.8 hrs

C
Re: Al can complete a particular job in 8 hours. Boris can   [#permalink] 15 Nov 2016, 18:56
Similar topics Replies Last post
Similar
Topics:
3 Working at a constant rate, Sam can finish a job in 3 hours. Mark, als 4 03 Jan 2016, 11:46
110 Machine A can complete a certain job in x hours. Machine B 29 05 Nov 2011, 12:23
8 A can complete the job in 2 hours and B can complete the sam 6 17 Mar 2011, 04:21
8 Machine A working alone can complete a job in 3 1/2 hours 7 08 Mar 2011, 01:23
1 Frances can complete a job in 12 hours, and Joan can 5 17 Sep 2010, 01:56
Display posts from previous: Sort by