<PRE><B>Question 623178</B>
In his motorboat, man can go downstream in 1 hour less time than he can go upstream the same distance.
 If the rate of the current is 5kph, how fast can he travel in still water if it takes him 2 hours to travel upstream the given distance?
:
Let s = boat speed in still water
then
(s+5) = effective speed downstream
(s-5) = effective speed upstream
:
write a distance equation, dist = speed/speed
:
Dist upstream = dist downstream
2(s-5) = 1(s+5)
2s - 10 = s + 5
2s - s = 5 + 10
s = 15 km/h in still water
:
:
Check solution by finding the distances
2(15-5) = 20 km
1(15+5) = 20 km</PRE>