Question

3.Плот проплывает от пункта А до пункта В за 30 часов, а катер за 3 часа. За какое время катер преодолеет путь от В до А.

Answer 1

Скорость плота=скорости течения реки ,S путь от А до В
Vтеч=S/30
x собственная скорость катера
x+S/30 скорость по теч из А в В
x-S/30 скорость против из В в А
S/   x+S/30 =30S /    30x+S  время по теч
S/  x-S/30 = 30S/   30x-S   время против
30S /     30x+S  =3
90x+3S=30S
90x=27S
x=27S/90=3S/10 подставим в выражение (время против течения)
30S /   30 *(3S/10)-S=30S/   90S/10  -S=30S/8S=30/8=15/4=3 3/4 часа

Answer 2

За 3 часа, тут не нужна время плота

Answer 3

Given Information:

- A boat travels from point A to point B in 30 hours. - A motorboat travels from point B to point A in 3 hours.

Calculation:

To find out how long it takes for the motorboat to travel from point A to point B, we can use the concept of relative speed.

Let's assume the distance between point A and point B is d.

The speed of the boat is given by d/30 (distance divided by time) and the speed of the motorboat is given by d/3.

When the boat and the motorboat are traveling towards each other, their speeds are added. So the relative speed is (d/30) + (d/3).

The time taken to cover the distance d is given by d/((d/30) + (d/3)).

Simplifying the expression, we get d/(d/10) = 10.

Therefore, the motorboat will cover the distance from point B to point A in 10 hours.

Answer:

The motorboat will take 10 hours to cover the distance from point B to point A.

Note: The sources provided did not contain relevant information for this specific calculation.