Question

334. Теплоход проплывает расстояние между двумя городами по течению реки за 4 ч, а такое же расстояние по озеру - за 5ч. Сколько времени потребуется плоту, чтобы преодолеть расстояние между этими двумя городами? ПОМОГИТЕЕЕЕЕЕ ПОЖАЛУЙСТААА​

Answer 1

Ответ: плот преодолеет расстояние между двумя городами по реке за 20 часов

Пошаговое объяснение:

пусть расстояние между городами равно S, тогда скорость по течению реки теплохода равна S/4 км/ч, а без течения S/5 км/ч, а разница между этими скоростями равна скорости течения;

S/4-S/5=(5S-4S)/20=S/20 км/ч - скорость течения;

это значит, что плот, который движется со скоростью течения преодолеет заданное расстояние за 20 часов;

Ответ: плот преодолеет расстояние между двумя городами по реке за 20 часов.

Answer 2

Problem Analysis

We are given that a boat can travel a certain distance between two cities along a river in 4 hours and the same distance across a lake in 5 hours. We need to determine how long it would take a raft to cover the same distance between the two cities.

Solution

Let's assume that the distance between the two cities is d.

We are given that the boat can travel the distance along the river in 4 hours, so its speed relative to the water is d/4.

We are also given that the boat can travel the same distance across the lake in 5 hours, so its speed relative to the water is d/5.

Since the speed of the boat relative to the water is the same in both cases, we can equate the two speeds:

d/4 = d/5

To find the time it would take for the raft to cover the same distance, we need to determine its speed relative to the water.

Let's assume the speed of the raft relative to the water is v.

The speed of the raft relative to the water is the same as the speed of the boat relative to the water, so we can write:

v = d/4 = d/5

Now, we can calculate the time it would take for the raft to cover the distance d using its speed v:

Time = Distance / Speed

Time = d / v

Substituting the value of v from above, we get:

Time = d / (d/4) = 4

Therefore, it would take the raft 4 hours to cover the distance between the two cities.

Answer

The raft would take 4 hours to cover the distance between the two cities.