SOLUTION: A certain river has a current of 3 miles per hour. A boat takes twice as long to travel upstream between two points as it does to travel downstream between the same two points. Wha
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Question 475279: A certain river has a current of 3 miles per hour. A boat takes twice as long to travel upstream between two points as it does to travel downstream between the same two points. What is the speed of the boat in still water?
a. 3 miles per hour
b. 6 miles per hour
c. 9 miles per hour
d. 12 miles per hour
e. The speed can't be determined from the given information.
HELP ME PLS.......... :) & explain it pls.. :)
Thanks. Answer by mananth(16946) (Show Source):
You can put this solution on YOUR website! boat speed = x mph
current = 3 mph
against current speed = x-3
with current speed = x+3
let y be the distance .
downstream t= y/(x+3)............1
upstream 2t = y/(x-3)............2
multiply (1) by 2
2t=2y/(x+3)
Therefore y/(x-3)=2y/(x+3)
1/(x-3)=2/(x+3)
2(x-3)=x+3
2x-6=x+3
2x-x=6+3
x=9 mph speed of boat
m.ananth@hotmail.ca
