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# If it takes 6 people 6 days to do a job? How many days would

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Intern
Joined: 12 May 2005
Posts: 29
If it takes 6 people 6 days to do a job? How many days would  [#permalink]

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09 May 2010, 08:48
00:00

Difficulty:

(N/A)

Question Stats:

92% (00:24) correct 8% (00:10) wrong based on 20 sessions

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If it takes 6 people 6 days to do a job? How many days would it take 2 people working at the same rate to do the job?

My question is why can't we set up a proportion for this problem and solve it? My equation is:
6 people---6 days
1 person---x=6/6=1 day ??

But the above strategy is obviously wrong!! Can someone please explain why?I am missing something here.

OA:
18 days
Manager
Joined: 05 Mar 2010
Posts: 173

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09 May 2010, 09:36
6 person do a job in 6 days
1 person do the same job in 6*6 = 36 days
2 person in 36/2 = 18 days

Another way -

6 person day job in 6 days
so in day they do 1/6 of the total work
1 person in one day will do 1/6*6 = 1/36 of total work
so 2 person in one day will do 2/36 = 1/18 of total work
Hence, 2 person will take 18 days to finish the same job

Hope this helps
_________________

Success is my Destiny

Math Expert
Joined: 02 Sep 2009
Posts: 52161

### Show Tags

09 May 2010, 09:42
srichaks wrote:
Q: If it takes 6 people 6 days to do a job? How many days would it take 2 people working at the same rate to do the job?

My question is why can't we set up a proportion for this problem and solve it? My equation is:
6 people---6 days
1 person---x=6/6=1 day ??

But the above strategy is obviously wrong!! Can someone please explain why?I am missing something here.

OA:18 days

Red part is not correct:
6 people need 6 days to do the job;
6 people in one day do 1/6 of the job;
1 person in one day does 1/6*6=1/36 of the job.

2 persons in 1 day do 2*1/36=1/18 of the job.
To do the whole job the'll need 18 days.

But the above can be done in easier way:
Time, rate and job in work problems are in the same relationship as time, speed (rate) and distance.

Time*Rate=Distance
Time*Rate=Job

We are told that combined rate decreased 3 times, therefore to do the same job, it would take 3 times more days (time). So, now it would take 6*3=18 days.

Hope it helps.
_________________
Manager
Joined: 16 Feb 2010
Posts: 135

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18 May 2010, 16:01
time and no.of men required are always inversely propotional, perhaps you are missing that one...
Intern
Joined: 21 Feb 2010
Posts: 3

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21 May 2010, 05:59
simple logic is that 6 people does some work in 6 days so 1 man will do it in 36 days and 2 will do it in 18 days.
Intern
Joined: 04 May 2013
Posts: 44
Re: If it takes 6 people 6 days to do a job? How many days would  [#permalink]

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03 Aug 2013, 11:05
I think I should be worried if I get problems like this on GMAT.
Right?
VP
Status: It's near - I can see.
Joined: 13 Apr 2013
Posts: 1363
Location: India
GMAT 1: 480 Q38 V22
GPA: 3.01
WE: Engineering (Consulting)
Re: If it takes 6 people 6 days to do a job? How many days would  [#permalink]

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12 May 2018, 01:10
srichaks wrote:
If it takes 6 people 6 days to do a job? How many days would it take 2 people working at the same rate to do the job?

My question is why can't we set up a proportion for this problem and solve it? My equation is:
6 people---6 days
1 person---x=6/6=1 day ??

But the above strategy is obviously wrong!! Can someone please explain why?I am missing something here.

OA:
18 days

6 people 6 days = 1 job

1 person 1 day = 1/36 job

2 person 1 day = 1/36*2 = 1/18 job

So time = 18 days

_________________

"Do not watch clock; Do what it does. KEEP GOING."

Intern
Joined: 01 Apr 2012
Posts: 16
Re: If it takes 6 people 6 days to do a job? How many days would  [#permalink]

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28 May 2018, 01:18
srichaks wrote:
If it takes 6 people 6 days to do a job? How many days would it take 2 people working at the same rate to do the job?

My question is why can't we set up a proportion for this problem and solve it? My equation is:
6 people---6 days
1 person---x=6/6=1 day ??

But the above strategy is obviously wrong!! Can someone please explain why?I am missing something here.

OA:
18 days

6 people 6 days total mandays 6 * 6 = 36
So 2 people would take 36/2 = 18 days
Re: If it takes 6 people 6 days to do a job? How many days would &nbs [#permalink] 28 May 2018, 01:18
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