Author 
Message 
TAGS:

Hide Tags

Manager
Joined: 25 May 2006
Posts: 227

Al can complete a particular job in 8 hours. Boris can [#permalink]
Show Tags
11 Jul 2006, 21:20
3
This post received KUDOS
21
This post was BOOKMARKED
Question Stats:
66% (03:26) correct
34% (02:57) wrong based on 489 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
Official Answer and Stats are available only to registered users. Register/ Login.
_________________
Who is John Galt?



Manager
Joined: 22 Jan 2012
Posts: 88
Location: India
Concentration: General Management, Technology
GPA: 3.3
WE: Engineering (Consulting)

Re: Al can complete a particular job in 8 hours. Boris can [#permalink]
Show Tags
19 Mar 2012, 20:28
5
This post received 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 which is more helpful infact.. Ill be posting good questions as many as I can...
Towards Success



Director
Joined: 10 Oct 2005
Posts: 718
Location: Madrid

Re: PS: Work Problem [#permalink]
Show Tags
11 Jul 2006, 21:43
2
This post received 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



Math Expert
Joined: 02 Sep 2009
Posts: 39666

Re: Al can complete a particular job in 8 hours. Boris can [#permalink]
Show Tags
06 May 2012, 03:16
2
This post received 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. Answer: C. Hope it's clear.
_________________
New to the Math Forum? Please read this: All You Need for Quant  PLEASE READ AND FOLLOW: 12 Rules for Posting!!! Resources: GMAT Math Book  Triangles  Polygons  Coordinate Geometry  Factorials  Circles  Number Theory  Remainders; 8. Overlapping Sets  PDF of Math Book; 10. Remainders  GMAT Prep Software Analysis  SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS)  Tricky questions from previous years.
Collection of Questions: PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.
What are GMAT Club Tests? Extrahard Quant Tests with Brilliant Analytics



Senior Manager
Joined: 30 Aug 2009
Posts: 287
Location: India
Concentration: General Management

Re: Work and time [#permalink]
Show Tags
03 Dec 2009, 23:49
1
This post received 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" Please explain! 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 192/160 = 68/160 A does 1/16 part of second job in 1hr so he would require (68/160)/(1/16) = 6.8hrs



Manager
Joined: 12 Feb 2012
Posts: 135

Re: Al can complete a particular job in 8 hours. Boris can [#permalink]
Show Tags
05 May 2012, 07:38
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.



Intern
Joined: 03 Apr 2012
Posts: 27

Re: Al can complete a particular job in 8 hours. Boris can [#permalink]
Show Tags
07 May 2012, 18:39
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. Answer: C. 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: 39666

Re: Al can complete a particular job in 8 hours. Boris can [#permalink]
Show Tags
08 May 2012, 01:09
jayaddula wrote: 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. Answer: C. 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.
_________________
New to the Math Forum? Please read this: All You Need for Quant  PLEASE READ AND FOLLOW: 12 Rules for Posting!!! Resources: GMAT Math Book  Triangles  Polygons  Coordinate Geometry  Factorials  Circles  Number Theory  Remainders; 8. Overlapping Sets  PDF of Math Book; 10. Remainders  GMAT Prep Software Analysis  SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS)  Tricky questions from previous years.
Collection of Questions: PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.
What are GMAT Club Tests? Extrahard Quant Tests with Brilliant Analytics



Manager
Joined: 26 Dec 2011
Posts: 113

Re: Al can complete a particular job in 8 hours. Boris can [#permalink]
Show Tags
10 May 2012, 06:05
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 = 2w46w/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)

Re: Al can complete a particular job in 8 hours. Boris can [#permalink]
Show Tags
21 Sep 2012, 06:06
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: 39666

Re: Al can complete a particular job in 8 hours. Boris can [#permalink]
Show Tags
21 Sep 2012, 06:22
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?"
_________________
New to the Math Forum? Please read this: All You Need for Quant  PLEASE READ AND FOLLOW: 12 Rules for Posting!!! Resources: GMAT Math Book  Triangles  Polygons  Coordinate Geometry  Factorials  Circles  Number Theory  Remainders; 8. Overlapping Sets  PDF of Math Book; 10. Remainders  GMAT Prep Software Analysis  SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS)  Tricky questions from previous years.
Collection of Questions: PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.
What are GMAT Club Tests? Extrahard Quant Tests with Brilliant Analytics



Intern
Joined: 05 Mar 2014
Posts: 9

Re: Al can complete a particular job in 8 hours. Boris can [#permalink]
Show Tags
29 Mar 2014, 16:04
Answer C:
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
Answer C



SVP
Status: The Best Or Nothing
Joined: 27 Dec 2012
Posts: 1857
Location: India
Concentration: General Management, Technology
WE: Information Technology (Computer Software)

Re: Al can complete a particular job in 8 hours. Boris can [#permalink]
Show Tags
30 Oct 2014, 01:16
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\(= \frac{17}{40} * 16 = 6.8\) Answer = C Bunuel: Kindly update OA .......
_________________
Kindly press "+1 Kudos" to appreciate



CEO
Joined: 17 Jul 2014
Posts: 2524
Location: United States (IL)
Concentration: Finance, Economics
GPA: 3.92
WE: General Management (Transportation)

Re: Al can complete a particular job in 8 hours. Boris can [#permalink]
Show Tags
07 Dec 2015, 18:49
the wording of the question is terrible...



Manager
Joined: 03 Apr 2013
Posts: 179

Re: Al can complete a particular job in 8 hours. Boris can [#permalink]
Show Tags
19 Jul 2016, 04:50
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: DONE!
Joined: 05 Sep 2016
Posts: 409

Re: Al can complete a particular job in 8 hours. Boris can [#permalink]
Show Tags
15 Nov 2016, 19:56
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 8046 = 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, 19:56







