Question 396036: Joseph took 20 minutes to drive his boat upstream to his favorite fishing spot. Coming back later that day, at the same boat speed, took him 15 minutes. If the currnet in that part of the river is 5 mph, what was his boat speed?
Answer by mananth(16946)   (Show Source):
You can put this solution on YOUR website! Joseph took 20 minutes to drive his boat upstream to his favorite fishing spot. Coming back later that day, at the same boat speed, took him 15 minutes. If the currnet in that part of the river is 5 mph, what was his boat speed?
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let boat speed = x mph
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upstream speed = x-5 mph
downstream speed = x+5 mph
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distance is same.
d=rt
20 minutes = 1/3 hours
15 minutes = 1/4 hour
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1/3(x-5)= 1/4(x+5)
cross multiply
4(x-5)=3(x+5)
4x-20=3x+15
4x-3x=35
x= 35 mph speed of boat
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m.ananth@hotmail.ca
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