Ashi can swim in still water at the rate of 6km per hour. After swimming in a stream, she realized that she takes twice the time to go upstream as she takes to go downstream. What is speed of the current?

2 Km/hr

Let,

Speed of Ashi in still water i.e. x = 6km/hr 

Speed of stream/current - y

Upstream speed i.e. x - y = 6 - y km/hr

Downstream speed i.e. x + y = 6 + y km/hr

According to the question:

T = \(\frac{ D}{6 + y }\) --------1st equation  ( downstream time)

2T = \(\frac{ D}{6 - y }\) --------2nd equation  ( upstream time)

It can be deduced from the above equations that:

\(\frac{ 2D}{6 + y }\) = \(\frac{ D}{6 - y }\)

\(\frac{ 2}{6 + y }\) = \(\frac{ 1}{6 - y }\)

12 - 2y = 6 + y

3y = 6

y = 2 km/hr