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Question 563720:  If three people working together can clean an office suite in two hours, how long will it take a crew of four people to clean the office? 
 Found 2 solutions by  solver91311, bucky: Answer by solver91311(24713)      (Show Source): 
You can  put this solution on YOUR website! 
 
 
3 people clean 1 office in 2 hours, so
 
 
3 people clean 1/2 of an office in 1 hour, so
 
 
1 person cleans 1/6 of an office in 1 hour, so
 
 
4 people clean 4/6 = 2/3 of an office in 1 hour, so
 
 
4 people clean 1 office in 3/2 of an hour, i.e. 1 hour 30 minutes.
 
 
John 
  
My calculator said it, I believe it, that settles it 
 
 
 Answer by bucky(2189)      (Show Source): 
You can  put this solution on YOUR website! Three people clean the office in 2 hours means that it takes 6 person-hours of work to clean the office (3 persons times 2 hours = 6 person-hours). 
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So 4 persons will need to work 6 person-hours to clean the office.  
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To find the number of hours 4 persons need to work to complete 6 person-hours, divide 4 persons into 6 person-hours and you get the answer of 1.5 hours (4 into 6 = 1.5). 
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Or if you prefer, since a half hour is 30 minutes, 1.5 hours is the same as 1 hour and 30 minutes for the 4 persons to completely clean the office. 
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Hope this helps you to understand the problem. 
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