Annie rows 10km downstream in 2h. On the return trip, it takes her 4h to travel 8km. Find the average rowing speed and the speed of the current.

Question

Annie rows 10km downstream in 2h. On the return trip, it takes her 4h to travel 8km. Find the average rowing speed and the speed of the current.

Answer 1

WE have two unknowns, the rowing speed and the river's current speed.

 

Let's let r = rowing speed and c= current speed. Also, let's use the basic distance = time * speed formula.

 

In our first equation  we know Annie rowed downstream 10 km in 2 hours. So, 10 = 2 *(c + r). On the way back 8 = 4 * (r - c) because she is rowing against the current.

 

Can you solve the two equations to get c = 1.5 km/hr and r = 3.5 km/hr?