Question

a man can row boat at the rate of 4km/hr in still water He takes thrice as much time in going 30 km upstream as in going 30 km downstream Find the speed of the stream?

Answer 1

Answer:

Step-by-step explanation:

Answer 2

Answer:

Speed of the stream = 2 km/hr

Step-by-step explanation:

Let the speed of the stream = x km/hr

speed of the boat in still water = 4 km/hr

Speed upstream = (4-x) km/hr

Speed downstream = (4+x) km/hr

$Time \: taken \:to \:cover \:30\:km \: upstream = \frac{30}{4-x}\:hrs$

$Time \: taken \:to \:cover \:30\:km \: downstream = \frac{30}{4+x}\:hrs$

But, According to the problem given,

$3\times\frac{30}{4+x}=\frac{30}{4-x}$

$\implies 3(4-x) =4+x$

$\implies 12 - 3x = 4+x$

$\implies 12-4 = x+3x$

$\implies 8 = 4x$

$\implies \frac{8}{4}= x$

$\implies x = 2$

Therefore,

Speed of the stream = x = 2 km/hr

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