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Victor's job requires him to complete a series of identical [#permalink]
11 Sep 2011, 13:17

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Difficulty:

65% (hard)

Question Stats:

66% (04:07) correct
34% (02:49) wrong based on 158 sessions

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'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?

Thanks in advance! _________________

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

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?

Thanks in advance!

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.

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

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 _____________________________________________________________________________

Re: Victor's job requires him to complete a series of identical [#permalink]
24 Mar 2013, 02:07

Expert's post

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?

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

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 _____________________________________________________________________________

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

Actually I already did.

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).

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 _____________________________________________________________________________

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

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

Re: Victor's job requires him to complete a series of identical [#permalink]
23 Oct 2013, 23:42

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.

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

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

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Re: Victor's job requires him to complete a series of identical
[#permalink]
13 Jan 2014, 08:16