Question

За 3 часа лодка проплыла 51,6 км против течения реки.Какое расстояние проплывет лодка по течению реки за 4,5 часа,если скорость течения равна 1,4 км/ч?

Answer 1

1) 51,6 : 3 = 17,2 км/ч - скорость лодки против течения
2) 17,2 + 1,4 = 18,6 км/ч - собственная скорость лодки
3) 18,6 + 1,4 = 20 км/ч - скорость лодки по течению
4) 20 * 4,5 = 90 км - проплывёт лодка за 4,5 ч по течению реки
Ответ: 90 км

Answer 2

Problem Analysis

We are given that a boat traveled 51.6 km against the current of a river in 3 hours. We need to find the distance the boat will travel with the current of the river in 4.5 hours, given that the current speed is 1.4 km/h.

Calculation

To solve this problem, we can use the formula: distance = speed × time.

Let's calculate the speed of the boat against the current using the given information. We know that the boat traveled 51.6 km in 3 hours, so the speed against the current can be calculated as follows:

Speed against the current = distance / time = 51.6 km / 3 hours.

Now, let's calculate the speed of the boat with the current. We know that the current speed is 1.4 km/h, so the speed of the boat with the current can be calculated as follows:

Speed with the current = speed against the current + current speed = (51.6 km / 3 hours) + 1.4 km/h.

Finally, we can calculate the distance the boat will travel with the current in 4.5 hours using the speed with the current:

Distance with the current = speed with the current × time = [(51.6 km / 3 hours) + 1.4 km/h] × 4.5 hours.

Let's calculate the distance using the given values.

Calculation Results

Using the given values, the distance the boat will travel with the current in 4.5 hours is approximately 85.2 km.

Answer

Therefore, the boat will travel approximately 85.2 km with the current of the river in 4.5 hours, given that the current speed is 1.4 km/h.