9514 1404 393
Answer:
- kayak: 12 mph
- current: 2 mph
Step-by-step 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.
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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.
