SOLUTION: John�s boat travels 7 km/hour in still water. He travels 45 km upstream and 45 km downstream in a total time of 14 hours. What is the speed of the river?

Question 857644: John�s boat travels 7 km/hour in still water. He travels 45 km upstream and
45 km downstream in a total time of 14 hours. What is the speed of the river?
Answer by mananth(16946) (Show Source): You can put this solution on YOUR website!
boat speed = 7 km/h
current speed = x km/h

against current = 7 - x
with current = 7 + x

Total distance = 45 miles Total Time= 14.00 hours
Time upstream + time downstream = 14 hours

45 /( 7 - x )+ 45 /( 7 + x )= 14
45 ( 7 + x )+ 45 ( 7 - x )= 14.00 ( 49 - 1 X^2 )
315 + 45 x + 315 -45 x = 686 - 14 X^2
630 - -686 = -14 X^2
-56 = -14 X^2
-14 X^2= -56
X^2 = 4
X = +/- 2
speed of boat = 2km/h
RELATED QUESTIONS
the speed of a boat in still water is 16 km/h.The boat travels 43 km upstream and 45 km... (answered by mananth)

The current in a stream moves at a speed of 3km/h. A boat travels 40 km upstream and 40... (answered by josmiceli)

A boat moves 28 km/h in still water. It travels 80 km upstream and 80 km downstream in a... (answered by mananth)

The current in a stream moves at a speed of 5 km/h. A boat travels 39 km upstream and 39... (answered by Alan3354)

The speed of a boat in still water is 10 km/h. The boat travels 12 km upstream and 28 km... (answered by jorel1380)

The speed of a boat in still water is 8 km/h. It travels 60 km upstream and 60 km... (answered by mananth,ankor@dixie-net.com,Alan3354)

A boat travels 45 kms. upstream and then returns to the dock traveling 45 kilometers... (answered by lwsshak3)

Manny can paddle his canoe at a rate of 7 miles per hour in still water. he travels 45... (answered by ankor@dixie-net.com)

The current of a stream moves at a speed of 5km/hr. The boat travels 31 km upstream and... (answered by stanbon)