SOLUTION: Find the speed of the current of a river if a boat travels 12 mph, taking 1 hr 4 min to go 6 miles upstream and return 6 miles downstream.Please show me step by step.Thanks.

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Question 578035: Find the speed of the current of a river if a boat travels 12 mph, taking 1 hr 4 min to go 6 miles upstream and return 6 miles downstream.Please show me step by step.Thanks.
Answer by mananth(16946) (Show Source):
You can put this solution on YOUR website!
Boat speed = 12 mph
current speed = x mph

against current =12-x mph
with current = 12+x mph

Total distance =6 miles one way. Total Time= 1.07 hours
1 hour 4 minutes = 1 1/15 minutes = 1.07 hours
Time upstream + time downstream =1.07

6/(12-x)+6/(12+x)=1.07
multiply eaquation by (12+x)(12-x) = 144 -x^2
6(12+x)+6(12-x)=1.07(144-X^2)
72+6x+72-6x =153.65-1.07X^2
144 - -153.65 = - 1.07 X^2
-9.65 =1.07 X^2
1.07X^2 =9.65
x=
x= 3.01 mph
speed of current = 3 mph
m.ananth@hotmail.ca