Question 292349:  If it takes 3 people 4 hours to clean a warehouse, how long will it take 4 people to clean the warehouse? 
 Found 2 solutions by  Edwin McCravy, oberobic: Answer by Edwin McCravy(20064)      (Show Source): 
You can  put this solution on YOUR website! If it takes 3 people 4 hours to clean a warehouse, how long will it take 4 people to clean the warehouse? 
Since it takes 3 people 4 hours to clean a warehouse, it would take
1 person 3 times as long as that to clean a warehouse, or 12 hours,
and it would therefore take 4 people   as long as it would 
take 1 person or 3 hours.
Edwin 
 
 
 Answer by oberobic(2304)      (Show Source): 
You can  put this solution on YOUR website! There is insufficient information to answer the question.  I depends on how fast the fourth person can work.  Perhaps he/she can work twice as fast as the others?  Or only half as fast? 
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If we make the BIG assumption that everyone works at the same speed, and no one can go faster or slower than another, then we can solve the problem.  But that is a BIG assumption. 
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If 3 people can do the work in 4 hours, then logically 4 people working at the same speed can do the job in 3 hours. 
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Looking at any work problem, you have to think about the sum of their labors = 1 job done to completion. 
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If it takes 4 hr, then 1/4 of the work is done per hr. 
If there are 3 people, then each is doing 1/12 of the work per hr. 
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With 4 people, their aggregate work = 4*1/12 = 1/3 per hr. 
So it takes them 3 hr. 
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Done. 
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