Determine the speed of the river flow if the boat travels along the current for 4.5 km in 0.5 hours

Determine the speed of the river flow if the boat travels along the current for 4.5 km in 0.5 hours, and against the current the same distance passes in 2.5 hours?

S = 4.5 km = 4500 m.

t1 = 0.5 h = 1800 s.

t2 = 2.5 h = 9000 s.

Vр -?

When the boat moves along the current, its speed relative to the coast will be the sum of: the boat’s speed in still water Vl and the current velocity Vp.

Vl + Vр = S / t1.

When the boat moves against the current, its speed relative to the coast will be the difference: the speed of the boat in still water Vl and the speed of the current Vp.

Vl – Vр = S / t2.

Vl + Vr = 4500 m / 1800 s = 2.5.

Vl – Vr = 4500 m / 9000 s = 0.5.

Vl = 2.5 – Vp.

2.5 – Vp – Vp = 0.5.

2.5 – 2 * Vp = 0.5.

2 * Vр = 2.

Vр = 1 m / s.

Answer: the speed of the river flow is Vр = 1 m / s.