Question

Julie and Eric row their boat (at a constant speed) 18 miles downstream for 3 hours helped by the current. Rowing at the same rate, the trip back against the current takes 6 hours. Find the rate of the boat in still water

Answer 1

answer: the crews rowing rate is 6 mph and the rate of the current is 3 mph

Explanation:

v the crew rowing rate

u rate of the current

downstream v + u = 13.5/1.5 = 9 mph

upstream v - u = 13.5/4.5 = 3 mph

u = 9 - v

v - ( 9 - v ) = 3

v - 9 + v = 3

2 v = 12

v 6 mph, u 9 - 6 = 3 mph