Radical Expressions

Question

A kayaker spends a morning paddling on a river. She travels 9 miles upstream and 9 miles downstream in a total of 6 hours. In still water, she can travel at an average speed of 4 miles per hour. What is the average speed of the river's current in miles per hour?

Answer 1

Answer 2

k = 4 mph

distance = rate of speed times time

current speed = 2 mph

4+2 = 6 mph down stream in 9/6 = 1.5 hours

4-2 = 2 mph upstream in 9/2 = 4.5 hours

1.5 + 4.5 = 6 hours total up and back