Question

ritu can row down stream 20km in 2hours, and upstream 4km in 2 hours. find her speed of rowing in still water and the speed of the current ​

Answer 1

Answer:

Speed of boat in still water= 6 km/hr

Speed of stream= 4 km/hr

Step-by-step explanation:

Let the speed of boat in still water be x km/hr

Let the speed of stream be y km/hr

Then,

Speed of boat downstream= x+y km/hr

Speed of boat upstream= x-y km/hr

Case 1:

Time taken to go downstream=  $\frac{20}{x+y}$ = 2 hours

$\frac{20}{x+y} =2$

$20=2(x+y)$

$x+y=10\\(1)$

Case 2:

Time taken to go upstream= $\frac{4}{x-y}$ = 2 hours

$\frac{4}{x-y} =2$

$4=2(x-y)$

$x-y=2\\(2)$

Now, adding (1) and (2)

$(x+y)+(x-y)=10+2$$x+y+x-y=12$

$2x=12$

$x=6$

Now, substituting the value of x in (1)

$(6)+y=10$

$y=10-6$

$y=4$

So,

$x=6\\y=4$

Hence,

Speed of boat in still water= 6 km/hr

Speed of stream= 4 km/hr

Answer 2

Answer:

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