Question

Туристы проплыли на лодке по течению реки 21 км, а по озеру на 12,4 км меньше. Определитесли скорость реки, если на путь по реке они затратами 3,5 часа, а на путь по озеру 2 часа.

Answer 1

Problem Analysis

To solve this problem, we need to determine the speed of the river. We are given the distances traveled on the river and the lake, as well as the time taken for each leg of the journey. We can use the formula: speed = distance / time to calculate the speed of the river.

Calculation

Let's calculate the speed of the river using the given information.

The distance traveled on the river is 21 km, and the time taken is 3.5 hours. The distance traveled on the lake is 12.4 km less than the river distance, which is 21 km - 12.4 km = 8.6 km. The time taken on the lake is 2 hours.

Using the formula speed = distance / time, we can calculate the speed of the river and the lake.

The speed of the river is 21 km / 3.5 hours = 6 km/h. The speed of the lake is 8.6 km / 2 hours = 4.3 km/h.

Conclusion

The speed of the river is 6 km/h.