The boat’s own speed is 21.3 km / h, its speed upstream of the river is 18.2 km / h.

The boat’s own speed is 21.3 km / h, its speed upstream of the river is 18.2 km / h. How far will the boat sail if it moves 2 hours 30 minutes along the river?

The speed of the boat is 21.3 km / h, its speed against the river flow is 18.2 km / h, we calculate the speed of the river flow:

21.3 – 18.2 = 3.1 (km / h) – current speed.

Let’s find the speed of the boat downstream: 21.3 + 3.1 = 24.4 (km / h) – speed of the boat downstream.

The time of movement of the boat is 2 hours 30 minutes, we translate into hours: 2 hours 30 minutes = 2 30/60 hours = 2 1/2 hours = 2.5 hours.

Let’s find the boat’s path downstream in 2.5 hours:

24.4 * 2.5 = 61 (km).

Answer: the distance of the boat is 61 km.