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Solve the following application problem. Be sure to show your system of equations and the steps to solve the problem.

Application Problem: It takes a boat 2 hours to go 16 miles downstream with the current and 4 hours to return against the current. Find the speed of the boat in still water and the speed of the current.

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sqdancefan

Answer:

  • boat: 6 mph
  • current: 2 mph

Step-by-step explanation:

The relationship between time, speed, and distance is ...

  speed = distance/time

For boat speed b and current speed c, the speed downstream is ...

  b +c = (16 mi)/(2 h) = 8 mi/h

The speed upstream is ...

  b -c = (16 mi)/(4 h) = 4 mi/h

Adding the two equations eliminates the c term:

  2b = 12 mi/h

  b = 6 mi/h . . . . . divide by 2

Solving the second equation for c, we get ...

  c = b -4 mi/h = 6 mi/h -4 mi/h = 2 mi/h

The speed of the boat in still water is 6 mi/h; the current is 2 mi/h.

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