Question

The speed of a boat in still water is 50 km/hr. If the speed of the boat against the stream is 31 km/hr, what is the speed of the stream?
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Answer 1

Answer:

If boat is moving opposite to direction of stream, then

Net speed of boat= Actual speed of boat-speed of stream

so, put values you get speed of stream 19km/hr

Answer 2

Speed of the stream is 19 km/hr.

The speed of a boat in still water is 50 km/hr. If the speed of the boat against the stream is 31 km/hr.

We have to find the speed of the stream.

Speed of boat against the stream means, it means boat is moving just opposite to the direction of stream.

Hence the speed of boat against the stream will be difference of speed of boat in still water to speed of stream.

If we assume, x is the speed of boat in still water and y is the speed of stream.

∴ speed of boat against stream = (x - y)

Here, speed of boat in still water, x = 50 km/hr

And speed of boat against stream, (x - y) = 31 km/hr

⇒50 - y = 31

⇒y = 19 km/hr

Therefore the speed of stream is 19 km/hr.