Question

Расстояние между пристанями A и B равно 96км.Из пристани A вниз по течению реки отправили плот. Одновременно с этим из пристани B навстречу с плотом отплыла моторная лодка и встретилась с ним через 4 часа. Какова собственная скорость (км/ч) лодки, если скорость течения реки равна 3км/ч

Answer 1

Найдем расстояние плота S=vt=4*3=12км

Найдем расстояние лодки S=96-12=84км

Теперь находим скорость лодки v=s/t=84/4=21км/ч

Answer 2

Problem Analysis

We are given that the distance between two ports, A and B, is 96 km. A raft is sent downstream from port A, while a motorboat sets off from port B to meet the raft. They meet after 4 hours. We need to determine the speed of the motorboat, given that the speed of the river current is 3 km/h.

Solution

Let's assume the speed of the motorboat is x km/h. Since the raft is moving downstream, its speed relative to the river current is the sum of the raft's speed and the speed of the river current. Therefore, the speed of the raft is 3 km/h.

We can set up the following equation to represent the distance traveled by the motorboat and the raft:

Distance = Speed × Time

For the motorboat: Distance = Speed of the motorboat × Time

For the raft: Distance = (Speed of the raft + Speed of the river current) × Time

Since the distance traveled by both the motorboat and the raft is the same (96 km), we can equate the two equations:

(Speed of the motorboat × Time) = ((Speed of the raft + Speed of the river current) × Time)

Simplifying the equation, we get:

Speed of the motorboat = (Speed of the raft + Speed of the river current)

Substituting the given values, we have:

Speed of the motorboat = (3 km/h + 3 km/h) = 6 km/h

Therefore, the speed of the motorboat is 6 km/h.

Answer

The speed of the motorboat is 6 km/h.