SOLUTION: THE CURRENT IN A RIVER IS 4MPH. A BOAT MOTORS 6 MILES UPSTREAM IN THE SAME TIME IT TAKES TO GO 12 MILES DOWNSTREAM. SPEED OF BOAT IN STILL WATER?

Question 283714: THE CURRENT IN A RIVER IS 4MPH. A BOAT MOTORS 6 MILES UPSTREAM IN THE SAME TIME IT TAKES TO GO 12 MILES DOWNSTREAM. SPEED OF BOAT IN STILL WATER?
Found 3 solutions by mananth, richwmiller, stanbon:
Answer by mananth(16946)   (Show Source): You can put this solution on YOUR website!
Let speed of boat in still water be x
Speed upstream will be x-4
Speed of boat down stream will be x+4
Time upstream = 6/ x-4 ( Time = distance / rate)
Time downstream = 12/x+4
Both these times are same
6/x-4 = 12 / x+4
6(x+4)=12(x-4)
6x+24=12x-48
6x=72
x= 12 mph the speed of boat in still water

Answer by richwmiller(17219)   (Show Source): You can put this solution on YOUR website!
Two questions.
How is this a rate of work problem?
Why are you shouting? When the ringing in my ears stops, I'll answer the problem.

Answer by stanbon(75887)   (Show Source): You can put this solution on YOUR website!
THE CURRENT IN A RIVER IS 4MPH. A BOAT MOTORS 6 MILES UPSTREAM IN THE SAME TIME IT TAKES TO GO 12 MILES DOWNSTREAM. SPEED OF BOAT IN STILL WATER?
------------------------------------------
Upstream DATA:
distance = 6 miles ; rate = b-4 mph ; time = 6/(b-4) hrs
----------------------------
Downstream DATA:
distance = 12 miles ; rate = b+4 mph ; time = 12(b+4) hrs
----------------------------
Equation:
time up = time down
6/(b-4) = 12/(b+4)
1/(b-4) = 2/(b+4)
b+4 = 2(b-4)
b+4 = 2b-8
b = 12 mph (boat speed in still water)
===========================================
Cheers,
Stan H.

RELATED QUESTIONS
the current in the lazy river moves at a rate of 4mph. vlads motors 6 miles upstream in... (answered by ewatrrr)
a boat takes the same amout of time to go 14 miles upstream as it does to go 16 miles... (answered by mananth)
the speed of a river is 4mph. if a boat travels 30 miles downstream in the same time it... (answered by TimothyLamb)
A boat can travel 12 miles upstream in the same amount of time it takes to travel 18... (answered by mananth,stanbon)
A boat goes 15 miles per hour in still water. If it can go 12 miles downstream in the... (answered by stanbon)
A boat goes 210 miles downstream in the same time it can go 180 miles upstream the speed... (answered by josmiceli)
A boat can travel on a river 7 miles upstream in the same time it takes to travel 19... (answered by ankor@dixie-net.com)
A boat travels 9 miles downstream in the same time it takes to go 6 miles upstream. If... (answered by lwsshak3)
1. The speed of a boat in still water is 10 mph. If it travels on a river 6 miles... (answered by Theo)