Question

ritu can row downstream 20km in 2hour .and upstream 4km in 2hrs . find her speed of rowing in still water and the speed of current​

Answer 1

Answer:

The speed in still water =6km/hr

The speed of stream =4km/hr

Step-by-step explanation:

Let the speed of the still water be x

And the speed of stream be y

So,

The speed when she goes downstream is 'x+y'

And speed upstream is 'x-y'

Now given in question,

She goes 20 km downstream in 2 hrs

So,

Distance/speed=time

i.e 20/x+y = 2

And also she take 2hr to row 4km upstream

So,

4/x-y =2

Now solve the two equations

x-y =2

And

x+y =10

From this,

The speed in still water =6km/hr

The speed of stream =4km/hr

i hope it will help u

Answer 2

Answer:

Let the speed of the Ritu in still water and the speed of the stream be x km/h and y km/h respectively.

Speed of ritu while rowing

$\\ \sf \: Upstream = \: (x - y) \: \: km/h \\ \\ \sf \: Downstream = \: (x + y) \: \: km/h$

$\large{\underline{\mathrm{\blue{According\:\:to\:\:the\:\: question\:\::-}}}}$

$\\ \sf \: 2 \: (x + y) = 20 \\ \\ \\ \implies \sf \: x + y = 10 \: \qquad \: - - - (i) \\ \\ \\ \sf \: 2 \: (x - y) = 4 \\ \\ \\ \implies \sf \: x - y = 2 \: \qquad \: - - - (2)$

By adding both the equations, we obtain -

$\\ \sf \: 2x = 12 \\ \\ \\ \implies \sf \: x = \frac{12}{2} \\ \\ \\ \implies \sf \green{x = 6}$

Putting the value of x in equation 1, we obtain -

$\\ \sf \: 6 + y = 10 \\ \\ \\ \implies \sf \: y = 10 - 6 \\ \\ \\ \implies \sf \red{y = 4}$

Hence, Ritu's speed in still water is 6 km/h and the speed of current is 4 km/h.