word problem

Question

A river is flowing downstream at a rate of 1 km/h. In still water Michael can swim at a rate of 2 km/h. Michael dives into the river and swims downstream then turns around and swims back to the starting point, taking 0.5 hours in total. How far did he swim?

Answer 1

Let x = one way distance

 

Distance = (Rate)(Time), so Time = Distance/Rate

 

Speed upstream = 2 - 1 = 1

Speed downstream = 2 + 1 = 3

 

Time upstream + Time downstream = Total time

 

x/1 + x/3 = 1/2

 

Multiply by the LCD, 6:    6x + 2x = 3

 

                                                   8x = 3      x = 3/8 km

 

Michael swam 3/8 km each way for a total of 3/4 km.