Question 756682
10 masons can build a wall working 7 hrs a day in 12 days. in how many days can a work be completed by 14 persons, working 8 hrs a day 
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# of days is inversely related to # of masons and inversely related to # of 
hours per day. So as # of masons increases # of days decreases.  Also as #
of hours per day increaes # of days to do the job decreases.  Therefore 
both the m and the h go into the denominator on the right side.

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d = k/(m*h)
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Solve for "k" using "10 masons can build a wall 
working 7 hrs a day in 12 days."
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12 = k/(10*7)
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k = 12*70 = 840
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Equation:
d = 840/(m*h)
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in how many days can a work be completed by 14 persons, working 8 hrs a day
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d = 840/(14*8)
d = 7.5 days
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Cheers,
Stan H.