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It took 3 hours to row a boat 18 km against the current. The return trip with the current took 1 1/2 hours. How do you find the speed of the rowboat in still water?

Answer 1

Julia Adams

The speed is 9 km/h.

Boat speed = Vb River speed = Vr

If it took 3 hours to cover 18km, the average speed #=18/3=6# km/h

For the return trip, the average speed is #=18/1.5=12# km/h

#{(Vb-Vr=6),(Vb+Vr=12):}#

According to the second equation,

#Vr=12-Vb#

Substituting in the first equation:

#Vb-(12-Vb)=6)#

#Vb-12+Vb=6#

#2Vb=6+12#

#Vb=18/2 = 9#

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Answer 2

Kennedy Adams

To find the speed of the rowboat in still water, you can use the formula:

Speed of rowboat in still water = (Distance traveled) / (Time taken)

For the trip against the current: Speed of rowboat in still water = (18 km) / (3 hours)

For the return trip with the current: Speed of rowboat in still water = (18 km) / (1.5 hours)

Calculate the speed of the rowboat in still water for both trips, then take the average of the two values to find the overall speed of the rowboat in still water.

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