Question

Ritu can row downstream 20 km in 2 hours and upstream 4 km in 2 hours . find her speee of rowing in still water and the speed of the current​

Answer 1

Answer:

Let, speed of Ritu in still water be x km/hr

and speed of current be y km/hr

Then speed downstream =(x+y) km/hr

speed upstream =(x−y) km/hr

we know,

$speed = \frac{distance}{time}$

$then \: \frac{20}{x + y} = 2 \: and \frac{4}{x - y} = 2 \\ = > x + y = 10......(1) \\ = > and \: x - y = 2......(2)$

adding both we get, 2x=12⇒x=6

Thus using (1) y=10−6=4

Hence the speed of Ritu in still water is 6 km/hr and the speed of the current is 4 km/hr.

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Answer 2

Let us consider,

Speed of Ritu is still water = x km/hr

Speed of Stream = y km/hr

Now, Speed of Ritu,

During,

Downstream = x + y km/hr

Upstream = x – y km/hr

As per the question given,

2(x + y) = 20

Or x + y = 10 ……….(1)

And, 2(x – y) = 4

Or x – y = 2…………(2)

Adding both the eq.1 and 2,

We get;

2x = 12

x = 6

Putting the value of x in eq.1,

we get;

y = 4

Therefore,

• Speed of Ritu is still water = 6 km/hr
• Speed of Stream = 4 km/hr