<PRE><B>Question 329422</B>
The current in a stream moves at a speed of 2 km/h. 
A boat travel 27 km upstream and 27 km downstream in a total of 17 hours. 
What is the speed of the boat in still water?
---
Upstream DATA:
distance = 27 km ; rate = (x-2) km/h ; time = d/r = 27/(x-2) hrs.
---------------------------
Downstream DATA:
distance = 27 km ; rate = (x+2) km/h ; time = 27/(x+2)
----------------------------
Equation:
time up + time down = 17
27/(x-2) + 27(x+2) = 17 hrs
-------------------------------
Multiply thru by (x-2)(x+2)
---
27(x+2) + 27(x-2) = 17(x^2-4)
54x = 17x^2 - 68x
---
17x^2 - 122x = 0
x(17x-122) = 0
Positive solution:
x = 122/17 = 7.1765 km/h (speed of the boat in still water)
==============================================================
Cheers,
Stan H.
</PRE>