a boat travels 20km upstream in a river in the same period of time as it takes to travel 30 km downstream . if the rate of the stream is 4 km/hr , find the speed of the boat in still water
Answers
Let the speed of boat in still water be x
Upstream:
Speed = (x - 40) km/h
Distance = 20 km
Time = Distance ÷ Speed
Time = 20 / ( x - 40)
Downstream:
Speed = (x + 40)
Distance = 30 km
Time = 30 / (x + 40)
Since both the timing are the same:
20 / ( x - 40) = 30 / (x + 40)
20(x + 40) = 30(x - 40)
20x + 80 = 30x - 120
10x = 200
x = 20 km/h
Answer: The speed of the boat in still water is 20 km/h
Answer:
Let the speed of boat in still water be x.
Step-by-step explanation:
Distance = 20 km
Time = Distance ÷ Speed
Time = 20 / ( x - 40)
Downstream:
Speed = (x + 40)
Distance = 30 km
Time = 30 / (x + 40)
Since both the timing are the same:
20 / ( x - 40) = 30 / (x + 40)
20(x + 40) = 30(x - 40)
20x + 80 = 30x - 120
10x = 200
x = 20 km/h
Answer: The speed of the boat in still water is 20 km/h