Question

in her kayak bunny can travel 70 miles downstream with the current in 5 hours. the return trip against the current takes 7 hours. find the speed of the kayak in Stillwater and the speed of the current​

Answer 1

9514 1404 393

Answer:

• kayak: 12 mph
• current: 2 mph

Explanation:

Bunny's rate downstream is ...

(70 mi)/(5 h) = 14 mi/h = k + c

Bunny's rate upstream is ...

(70 mi)/(7 h) = 10 mi/h = k -c

The kayak speed is the average of these:

(14 mi/h +10 mi/h)/2 = ((k +c) +(k -c))/2

(24 mi/h)/2 = 2k/2

12 mi/h = k

Then the current speed is ...

c = k -10 = 12 -10 = 2 . . . . mi/h

The still-water speed of the kayak is 12 mi/h; the speed of the current is 2 mi/h.

_____

Additional comment

World-class kayak paddlers will not maintain a speed more than 8 mi/h for that distance and/or time (140 miles in 12 hours). Bunny is exceptional.