Question

rahul can row downstream 20 km in 2 hours and upstream 4km in 2 hours . find his speed of rowing in still water and speed of current

Answer 1

Dear Student

Let the speed of Rahul in still water = x km/h
Speed of stream = y km/h
The downstream speed = (x+y) km /h
Upstream speed = (x-y) km /h
we know that
$$\begin{gathered} Speed=\frac{Dis\tan ce}{time} \\ time=\frac{Dis\tan ce}{time} \end{gathered}$$
According to question
$$\begin{gathered} for,downstream, \\ \frac{20}{x+y}=2 \\ 10=x+y----\left(1\right) \\ Upstream \\ \frac{4}{x-y}=2 \\ x-y=2----\left(2\right) \\ Adding(1)and(2) \\ 2x=12 \\ x=6 \\ Nowputx=6in\left(1\right) \\ 6+y=10 \\ y=4 \\ SpeedofRahulinStillwater=6km/h \\ Speedofstream=4km/h \end{gathered}$$


Regards