Question

Rohan can row downstream 20 km in 2 hours ,and upstream 4 km in 2 hours . Find his speed of rowing in still water and the speed of the current .

Answer 1

Hey friend, Harish here.

Here is your answer:

Given that,
 
$Distance\ traveled\ downstream= 20\ km$

$Time \ to \ travel\ downstream= 2\hrs$

$Distance\ traveled\ upstream = 4\ km$

$Time \ to \ travel\ upstream= 2\hrs$

To find,

Speed of rowing & Seep of water.

Solution,

Let speed of rowing be x & speed of water be y.

Then,

Speed during down stream = Speed of rowing + Speed of water

                                            = x + y .

Speed during up stream = Speed of rowing - Speed of water.

                                       = x - y

We know that,

 $Speed = \frac{Distance}{time}$

$Speed \ downstream = \frac{Distance\ traveled downstream}{Time taken}$

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

 $x+y = 10 \ \ \ \ \ \ \ - (i)$



$Speed \ upstream = \frac{Distance \ up steam }{Time taken}$

→$x-y = \frac{4}{2}$

→ $x-y = 2 \ \ \ \ \ \ \ - (ii)$


Now add (i) & (ii) equation.

Then ,

$x + y + x- y = 10 + 2$

→ $2x = 12$

→ $x = \frac{12}{2} = 6 \ km/hr$

Now substitute x in (i) or (ii) to get y.

Then,

$x - y= 2 = 6- 2 = 4\ km/hr$

Therefore speed of rowing is 6 km/hr & speed of water is 4km/hr .
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Hope my answer is helpful to you.

Answer 2

☺☺☺ Hope this Helps ☺☺☺

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