A steamer can go 12 km in still water in 25 minutes. One day, it went 11.25 km upstream and returned the same distance in downstream. If the difference between the time taken to travel upstream and downstream was 12.5 minutes, then what was the speed of stream in km per hour?
7.2
5.4
6.3
4.5
Explanation:
In still water, the speed of steamer =$\dfrac{12000}{25}$
=480 meter per minute=8 meters per second
Let the speed of stream=v m/sec
In upstream,the speed of streamer=(8-v)m/sec
In downstream,the speed of streamer=(8+v) m/sec
According to the question,
$\dfrac{11250}{8-v}-\dfrac{11250}{8+v}$=$12.5 \times 60 $=750 seconds.
By solving,v=2 meters per second
=$\dfrac{2 \times 18}{5}$=7.2km per hour
In still water, the speed of steamer =$\dfrac{12000}{25}$
=480 meter per minute=8 meters per second
Let the speed of stream=v m/sec
In upstream,the speed of streamer=(8-v)m/sec
In downstream,the speed of streamer=(8+v) m/sec
According to the question,
$\dfrac{11250}{8-v}-\dfrac{11250}{8+v}$=$12.5 \times 60 $=750 seconds.
By solving,v=2 meters per second
=$\dfrac{2 \times 18}{5}$=7.2km per hour