Question

Катер прошёл 30 км по течению реки за 2,5 часа и 20 км против течения реки также за 2,5 часа. Какова скорость реки?

Answer 1

1)12км/ч  скорость по течению
2)20:25=8 км/ч скорость против течения
ДОПУСТИМ что X км/x-это скорость реки
12-x=8+х
2х=4
х=2 км/ч скорость реки

Answer 2

Calculating the River's Speed

To calculate the speed of the river, we can use the formula: Boat's speed in still water = (Speed downstream + Speed upstream) / 2 Speed of the river = (Speed downstream - Speed upstream) / 2

Given: - Distance downstream = 30 km - Time downstream = 2.5 hours - Distance upstream = 20 km - Time upstream = 2.5 hours

Calculating Speed Downstream

The speed downstream can be calculated using the formula: Speed downstream = Distance downstream / Time downstream

Using the given values: Speed downstream = 30 km / 2.5 hours = 12 km/h

Calculating Speed Upstream

The speed upstream can be calculated using the formula: Speed upstream = Distance upstream / Time upstream

Using the given values: Speed upstream = 20 km / 2.5 hours = 8 km/h

Calculating the River's Speed

Now, we can calculate the speed of the river using the formulas mentioned earlier: Boat's speed in still water = (12 km/h + 8 km/h) / 2 = 10 km/h Speed of the river = (12 km/h - 8 km/h) / 2 = 2 km/h

Therefore, the speed of the river is 2 km/h.