Victor's job requires him to complete a series of identical : GMAT Problem Solving (PS)
Check GMAT Club Decision Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

 It is currently 22 Jan 2017, 15:10

### 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

# Victor's job requires him to complete a series of identical

Author Message
TAGS:

### Hide Tags

Senior Manager
Joined: 29 Jan 2011
Posts: 367
Followers: 0

Kudos [?]: 201 [5] , given: 87

Victor's job requires him to complete a series of identical [#permalink]

### Show Tags

11 Sep 2011, 13:17
5
KUDOS
8
This post was
BOOKMARKED
00:00

Difficulty:

65% (hard)

Question Stats:

67% (04:14) correct 33% (03:06) wrong based on 270 sessions

### HideShow timer Statistics

Victor's job requires him to complete a series of identical jobs. If Victor is supervised at work, he finishes each job three days faster than if he is unsupervised. If Victor works for 144 days and is supervised for half the time, he will finish a total of 36 jobs. How long would it take Victor to complete 10 jobs without any supervision?

A. 34
B. 52
C. 60
D. 70
E. 92
[Reveal] Spoiler: OA

Last edited by Bunuel on 24 Mar 2013, 01:55, edited 2 times in total.
Renamed the topic and edited the question.
Director
Joined: 01 Feb 2011
Posts: 755
Followers: 14

Kudos [?]: 115 [0], given: 42

### Show Tags

11 Sep 2011, 13:33
supervised not supervised

time per job t-3 t

In 144 days when victor was supervised for half of the time , he finished 36 jobs.

=> During 72 days of supervision he finished 36 jobs.

=> 36(t-3) = 72

=> t = 5

=> victor took 5 days to finish a each unsupervised job.

time taken by victor to finish 10 jobs with out supervision = 10t = 50
Senior Manager
Joined: 29 Jan 2011
Posts: 367
Followers: 0

Kudos [?]: 201 [0], given: 87

### Show Tags

11 Sep 2011, 13:39
Spidy001 wrote:
supervised not supervised

time per job t-3 t

In 144 days when victor was supervised for half of the time , he finished 36 jobs.

=> During 72 days of supervision he finished 36 jobs.

=> 36(t-3) = 72

=> t = 5

=> victor took 5 days to finish a each unsupervised job.

time taken by victor to finish 10 jobs with out supervision = 10t = 50

OA is 60 but.... there is some mistake with your solution
Director
Joined: 01 Feb 2011
Posts: 755
Followers: 14

Kudos [?]: 115 [1] , given: 42

### Show Tags

11 Sep 2011, 13:57
1
KUDOS
my bad. ignore the previous post. i thought the question said 36 jobs in 72 days of supervision.

Where as Questions says it took 36 jobs in 144 days out of which he worked halftime supervised.

Supervised not supervised
time per job t-3 days t days

=> jobs in 72 days of supervision + jobs in 72 days when not supervised = 36

=> 72/(t-3) + 72/t = 36

solving we get t = 1 or 6

=> t=6 ( t = 1 is not possible as t-3 would be negative)

=> time taken by victor each unsupervised job = 6 days.

=> time taken by victor to finish 10 unsupervised jobs = 10t = 60 days.
Manager
Status: Prepping for the last time....
Joined: 28 May 2010
Posts: 200
Location: Australia
Concentration: Technology, Strategy
GMAT 1: 630 Q47 V29
GPA: 3.2
Followers: 0

Kudos [?]: 28 [1] , given: 21

### Show Tags

12 Sep 2011, 01:34
1
KUDOS
60 days it is

72/ (x-3) + 72/x = 36

=> x^2 -7x+6 =0 => x= 1 or 6

X = 1 is omitted coz x-3 = -2 if x=1

so x=6 and time taken for 10 jobs under no supervision = 10x6 = 60
_________________

Two great challenges: 1. Guts to Fail and 2. Fear to Succeed

Senior Manager
Joined: 03 Aug 2011
Posts: 295
Concentration: Strategy, Finance
GMAT 1: 640 Q44 V34
GMAT 2: 700 Q42 V44
GMAT 3: 680 Q44 V39
GMAT 4: 740 Q49 V41
GPA: 3.7
WE: Project Management (Energy and Utilities)
Followers: 12

Kudos [?]: 69 [0], given: 916

### Show Tags

15 Nov 2012, 23:21
Guys,

I've made th same error as Spidy001. This advanced RTW problem is otherwise not that hard, but I wonder what strategies you apply in order to fully grasp the right meaning of the problem. At first, I also thought the 5 days per job scenario was right. Based on this problem, do you have any tips on that?

_________________

Thank you very much for reading this post till the end! Kudos?

Intern
Joined: 15 Nov 2012
Posts: 1
Concentration: Technology, Strategy
GPA: 2.6
Followers: 0

Kudos [?]: 1 [1] , given: 0

### Show Tags

15 Nov 2012, 23:57
1
KUDOS
bgpower wrote:
Guys,

I've made th same error as Spidy001. This advanced RTW problem is otherwise not that hard, but I wonder what strategies you apply in order to fully grasp the right meaning of the problem. At first, I also thought the 5 days per job scenario was right. Based on this problem, do you have any tips on that?

bgpower,

I can imagine why Spidy001 made that mistake. The question says that he was supervised for half that time, but it doesn't say that Victor did not work during the time he was unsupervised.
So, what the question intended to say was, Victor worked under supervision for 72 days and without supervision for the remaining 72. What Spidy001 has done is, he hasn't taken into account the 72 days that Victor worked without supervision.

Secondly, as data given to us was in the form of (days/job) and not (jobs/day), you should divide 72 by (t-3) and (t) rather than multiplying it.

This sort of an error can be avoided by simply taking a step back to understand what the question says and writing the facts down, rather than trying to hold them in your head.
Director
Joined: 03 Aug 2012
Posts: 916
Concentration: General Management, General Management
GMAT 1: 630 Q47 V29
GMAT 2: 680 Q50 V32
GPA: 3.7
WE: Information Technology (Investment Banking)
Followers: 23

Kudos [?]: 695 [0], given: 322

Re: Victor's job requires him to complete a series of identical [#permalink]

### Show Tags

23 Mar 2013, 22:00
siddhans wrote:
Victor's job requires him to complete a series of identical jobs. If Victor is supervised at work, he finishes each job three days faster than if he is unsupervised. If Victor works for 144 days and is supervised for half the time, he will finish a total of 36 jobs. How long would it take Victor to complete 10 jobs without any supervision?

I have a query

R T D
S (1/t) 72 (72/t)
U (1/(t+3) 72 (72/(t+3))

Total jobs = 36

(72/t) + [(72/(t+3)] = 36

=> 2/t + 2/(t+3) = 1
=> 2t + 6 + 2t = t^2 + 3t
=> t^2 - t - 6 = 0

t = 3 or t =-2 (can't be negative)
Hence , 3

Plz advice where I am wrong as I took the other way around by taking (t+3)

Rgds,
TGC
_________________

Rgds,
TGC!
_____________________________________________________________________
I Assisted You => KUDOS Please
_____________________________________________________________________________

Math Expert
Joined: 02 Sep 2009
Posts: 36601
Followers: 7097

Kudos [?]: 93471 [0], given: 10563

Re: Victor's job requires him to complete a series of identical [#permalink]

### Show Tags

24 Mar 2013, 02:07
targetgmatchotu wrote:
siddhans wrote:
Victor's job requires him to complete a series of identical jobs. If Victor is supervised at work, he finishes each job three days faster than if he is unsupervised. If Victor works for 144 days and is supervised for half the time, he will finish a total of 36 jobs. How long would it take Victor to complete 10 jobs without any supervision?

I have a query

R T D
S (1/t) 72 (72/t)
U (1/(t+3) 72 (72/(t+3))

Total jobs = 36

(72/t) + [(72/(t+3)] = 36

=> 2/t + 2/(t+3) = 1
=> 2t + 6 + 2t = t^2 + 3t
=> t^2 - t - 6 = 0

t = 3 or t =-2 (can't be negative)
Hence , 3

Plz advice where I am wrong as I took the other way around by taking (t+3)

Rgds,
TGC

We are told that if Victor is supervised at work, he finishes each job three days faster than if he is unsupervised.

Supervised = t days;
Unsupervised = (t + 3) days.

Victor to complete 10 jobs without any supervision will need 10(t + 3) = 60.

Hope it helps.
_________________
Director
Joined: 03 Aug 2012
Posts: 916
Concentration: General Management, General Management
GMAT 1: 630 Q47 V29
GMAT 2: 680 Q50 V32
GPA: 3.7
WE: Information Technology (Investment Banking)
Followers: 23

Kudos [?]: 695 [0], given: 322

Re: Victor's job requires him to complete a series of identical [#permalink]

### Show Tags

24 Mar 2013, 02:25
Bunuel wrote:
targetgmatchotu wrote:
siddhans wrote:
Victor's job requires him to complete a series of identical jobs. If Victor is supervised at work, he finishes each job three days faster than if he is unsupervised. If Victor works for 144 days and is supervised for half the time, he will finish a total of 36 jobs. How long would it take Victor to complete 10 jobs without any supervision?

I have a query

R T D
S (1/t) 72 (72/t)
U (1/(t+3) 72 (72/(t+3))

Total jobs = 36

(72/t) + [(72/(t+3)] = 36

=> 2/t + 2/(t+3) = 1
=> 2t + 6 + 2t = t^2 + 3t
=> t^2 - t - 6 = 0

t = 3 or t =-2 (can't be negative)
Hence , 3

Plz advice where I am wrong as I took the other way around by taking (t+3)

Rgds,
TGC

We are told that if Victor is supervised at work, he finishes each job three days faster than if he is unsupervised.

Supervised = t days;
Unsupervised = (t + 3) days.

Victor to complete 10 jobs without any supervision will need 10(t + 3) = 60.

Hope it helps.

Hi Bunuel

As I would follow the same method of RTW chart for any problem in TNW, it would be really helpful if you can QUOTE the error in my method .

Rgds,
TGC
_________________

Rgds,
TGC!
_____________________________________________________________________
I Assisted You => KUDOS Please
_____________________________________________________________________________

Math Expert
Joined: 02 Sep 2009
Posts: 36601
Followers: 7097

Kudos [?]: 93471 [0], given: 10563

Re: Victor's job requires him to complete a series of identical [#permalink]

### Show Tags

24 Mar 2013, 02:30
targetgmatchotu wrote:
Bunuel wrote:
targetgmatchotu wrote:
I have a query

R T D
S (1/t) 72 (72/t)
U (1/(t+3) 72 (72/(t+3))

Total jobs = 36

(72/t) + [(72/(t+3)] = 36

=> 2/t + 2/(t+3) = 1
=> 2t + 6 + 2t = t^2 + 3t
=> t^2 - t - 6 = 0

t = 3 or t =-2 (can't be negative)
Hence , 3

Plz advice where I am wrong as I took the other way around by taking (t+3)

Rgds,
TGC

We are told that if Victor is supervised at work, he finishes each job three days faster than if he is unsupervised.

Supervised = t days;
Unsupervised = (t + 3) days.

Victor to complete 10 jobs without any supervision will need 10(t + 3) = 60.

Hope it helps.

Hi Bunuel

As I would follow the same method of RTW chart for any problem in TNW, it would be really helpful if you can QUOTE the error in my method .

Rgds,
TGC

You calculated the time needed to complete 10 jobs WITH supervision (10t, less time) but we are asked to find the time needed to complete 10 jobs WITHOUT any supervision (10(t+3), more time).

Hope it's clear.
_________________
Director
Joined: 03 Aug 2012
Posts: 916
Concentration: General Management, General Management
GMAT 1: 630 Q47 V29
GMAT 2: 680 Q50 V32
GPA: 3.7
WE: Information Technology (Investment Banking)
Followers: 23

Kudos [?]: 695 [0], given: 322

Re: Victor's job requires him to complete a series of identical [#permalink]

### Show Tags

27 Sep 2013, 22:31
1
This post was
BOOKMARKED
Nice Question !

Took me a good amount of time !

Rate(Supervised) = 1/(t-3)
Rate(Unsupervised) = 1/(t)

72/(t-3) + 72 /(t) = 36

t=6 or t=1

Cannot be 1 as 't-3' would be negative then => t=6

Rate (UN) = 1/6

Rate * Time = work

1/6 * time = 10

Time = 10*6 = 60
_________________

Rgds,
TGC!
_____________________________________________________________________
I Assisted You => KUDOS Please
_____________________________________________________________________________

Manager
Status: Please do not forget to give kudos if you like my post
Joined: 19 Sep 2008
Posts: 128
Location: United States (CA)
Followers: 0

Kudos [?]: 75 [0], given: 257

Re: Victor's job requires him to complete a series of identical [#permalink]

### Show Tags

13 Oct 2013, 11:10
siddhans wrote:
Victor's job requires him to complete a series of identical jobs. If Victor is supervised at work, he finishes each job three days faster than if he is unsupervised. If Victor works for 144 days and is supervised for half the time, he will finish a total of 36 jobs. How long would it take Victor to complete 10 jobs without any supervision?

A. 34
B. 52
C. 60
D. 70
E. 92

My approach:
Since we are asked Unsupervised time, i make that as t (variable in question). This way i do not have to worry about other stuff.

S => 1/(t-3)
U => 1/t

72days Job S + 72days job U = 36job
72/t + 72/(t-3) = 36

now pick a number to that LHS = RHS
t=6 => 72\6 + 72\3 = 36

now asked is 10t=6*10 = 60.
_________________

[Reveal] Spoiler:

Manager
Joined: 26 Sep 2013
Posts: 221
Concentration: Finance, Economics
GMAT 1: 670 Q39 V41
GMAT 2: 730 Q49 V41
Followers: 4

Kudos [?]: 141 [0], given: 40

### Show Tags

17 Oct 2013, 11:14
raghavakumar85 wrote:
60 days it is

72/ (x-3) + 72/x = 36

=> x^2 -7x+6 =0 => x= 1 or 6

X = 1 is omitted coz x-3 = -2 if x=1

so x=6 and time taken for 10 jobs under no supervision = 10x6 = 60

edit: nevermind, had a mistake in my work
Senior Manager
Joined: 10 Mar 2013
Posts: 290
GMAT 1: 620 Q44 V31
GMAT 2: 690 Q47 V37
GMAT 3: 610 Q47 V28
GMAT 4: 700 Q50 V34
GMAT 5: 700 Q49 V36
GMAT 6: 690 Q48 V35
GMAT 7: 750 Q49 V42
GMAT 8: 730 Q50 V39
Followers: 11

Kudos [?]: 98 [0], given: 2405

Re: Victor's job requires him to complete a series of identical [#permalink]

### Show Tags

23 Oct 2013, 18:47
Why multiply the following by 72 instead of 144 seeing that Victor worked for 144 days?
Unsupervised rate + Supervised rate = Combined Rate
1/u + 1/(u-3) = 1/c
144*(1/c)=36
c = 4
c = (u^2-3u)/(2u-3) = 4

Isn't this the same logic that was done here: "http://gmatclub.com/forum/running-at-their-respective-constant-rates-machine-x-takes-98599.html"?
Math Expert
Joined: 02 Sep 2009
Posts: 36601
Followers: 7097

Kudos [?]: 93471 [1] , given: 10563

Re: Victor's job requires him to complete a series of identical [#permalink]

### Show Tags

23 Oct 2013, 23:42
1
KUDOS
Expert's post
TooLong150 wrote:
Why multiply the following by 72 instead of 144 seeing that Victor worked for 144 days?
Unsupervised rate + Supervised rate = Combined Rate
1/u + 1/(u-3) = 1/c
144*(1/c)=36
c = 4
c = (u^2-3u)/(2u-3) = 4

Isn't this the same logic that was done here: "http://gmatclub.com/forum/running-at-their-respective-constant-rates-machine-x-takes-98599.html"?

Victor's job requires him to complete a series of identical jobs. If Victor is supervised at work, he finishes each job three days faster than if he is unsupervised. If Victor works for 144 days and is supervised for half the time, he will finish a total of 36 jobs. How long would it take Victor to complete 10 jobs without any supervision?
A. 34
B. 52
C. 60
D. 70
E. 92

Rate when supervised = (job)/(time) = 1/t.
Rate when unsupervised = (job)/(time) = 1/(t+3).

For 144/2=72 days he is supervised and for 144/2=72 days he is unsupervised and does 36 jobs:
72/t + 72/(t+3) = 36 --> t=3 days --> t+3 = 6 days.

Victor to complete 10 jobs without any supervision will need 10(t + 3) = 60 days.

Hope it's clear.
_________________
Director
Joined: 23 Jan 2013
Posts: 579
Schools: Cambridge'16
Followers: 1

Kudos [?]: 42 [0], given: 40

Re: Victor's job requires him to complete a series of identical [#permalink]

### Show Tags

24 Oct 2013, 05:33
i tried to do with 72/x + 72/x+3=36 but it requires huge amount of time with use quadratic equation. Better to backsolve the answers with start from 60 (choice C). 60/10=6 and x=3, it wins
Manager
Joined: 25 Oct 2013
Posts: 173
Followers: 1

Kudos [?]: 56 [0], given: 56

Re: Victor's job requires him to complete a series of identical [#permalink]

### Show Tags

13 Jan 2014, 08:16
Temurkhon wrote:
i tried to do with 72/x + 72/x+3=36 but it requires huge amount of time with use quadratic equation. Better to backsolve the answers with start from 60 (choice C). 60/10=6 and x=3, it wins

Simplifying $$\frac{72}{{x}} + \frac{72}{{x+3}}=36$$ to $$\frac{2}{{x}}+\frac{2}{{x+3}}=1$$ may make it easier to solve the resultant quadratic equation.

We then have
$$x^2+3x=4x+6$$
$$x^2-x-6=0$$
$$(x-3)(x+2)=0$$ => $$x=3$$ (Supervised time). so 6 is unsupervised time per job. Therefore 6*10 = 60 hrs
_________________

Click on Kudos if you liked the post!

Practice makes Perfect.

GMAT Club Legend
Joined: 09 Sep 2013
Posts: 13504
Followers: 577

Kudos [?]: 163 [0], given: 0

Re: Victor's job requires him to complete a series of identical [#permalink]

### Show Tags

06 Jun 2015, 22:30
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.
_________________
Manager
Joined: 21 Jun 2014
Posts: 151
Location: United States
Concentration: General Management, Strategy
GMAT 1: 630 Q45 V31
GPA: 3.4
WE: Engineering (Computer Software)
Followers: 2

Kudos [?]: 69 [0], given: 59

Re: Victor's job requires him to complete a series of identical [#permalink]

### Show Tags

06 Jul 2015, 06:56
Also keep in mind the number of jobs =10 so answer has to be a multiple of 10 ,only C and D are the choices in this case .

Regards,
Manish Khare
_________________

Regards,
Manish Khare
"Every thing is fine at the end. If it is not fine ,then it is not the end "

Re: Victor's job requires him to complete a series of identical   [#permalink] 06 Jul 2015, 06:56

Go to page    1   2    Next  [ 22 posts ]

Similar topics Replies Last post
Similar
Topics:
21 Machine A takes 10 hours to complete a certain job and starts that job 8 23 Sep 2015, 21:32
29 At Supersonic Corporation, the time required for a machine to complete 11 06 Oct 2014, 03:17
11 Tom is on a certain diet that requires him to limit the 12 01 Mar 2014, 11:23
25 A carpenter worked alone for 1 day on a job that would take him 6 more 11 27 Jun 2011, 11:00
8 A can complete the job in 2 hours and B can complete the sam 6 17 Mar 2011, 04:21
Display posts from previous: Sort by