A girl can row 4 $\dfrac{2}{3} $ km/hr in still water and she finds that it takes her thrice as much time to row up than as to row down the same distance in river. The speed of the current is :
3 $\dfrac{1}{3} $ km/hr
3 $\dfrac{1}{9} $ km/hr
1 $\dfrac{1}{4} $ km/hr
4 $\dfrac{2}{3} $ km/hr
Explanation:
Let speed upstream be x kmph Then speed downstream = 3x kmph
Speed in still water = 1/2(3x+x)kmph=2xkmph
∴2x= 28/3
⇒x=14/3
So Speed upstream =14/3 km/hr
Speed downstream = 14 km/hr
Hence speed of the current = 1/2 (14−14/3)km/hr
= 14/3 km/h
=4 $\dfrac{2}{3} $ km/hr
Let speed upstream be x kmph Then speed downstream = 3x kmph
Speed in still water = 1/2(3x+x)kmph=2xkmph
∴2x= 28/3
⇒x=14/3
So Speed upstream =14/3 km/hr
Speed downstream = 14 km/hr
Hence speed of the current = 1/2 (14−14/3)km/hr
= 14/3 km/h
=4 $\dfrac{2}{3} $ km/hr