Question

Расстояние между двумя пристанями 45 км. Моторная лодка прошла это расстояние по течению реки за 3 ч, а против течения - за 5 ч. Найти скорость лодки в стоячей воде.

Answer 1

1)45/3=15
2)45/5=9
3)15-9/2=3 км/ч скор течения реки
4)15-3=12 км/ч скор лодки в стоячей воде

Answer 2

Calculating the Boat's Speed in Still Water

To find the speed of the boat in still water, we can use the concept of relative speed. The speed of the boat in still water can be represented as \( x \) and the speed of the river's current as \( y \).

Speed of the Boat Downstream

When the boat travels downstream, its speed is the sum of the speed of the boat in still water and the speed of the current. The time taken to cover the distance downstream is 3 hours.

Speed of the Boat Upstream

When the boat travels upstream, its speed is the difference between the speed of the boat in still water and the speed of the current. The time taken to cover the distance upstream is 5 hours.

Using the given information, we can set up the following equations:

1. For downstream travel: \[ (x + y) \times 3 = 45 \]

2. For upstream travel: \[ (x - y) \times 5 = 45 \]

To solve for \( x \) (the speed of the boat in still water), we can solve the system of equations.

Let's calculate the boat's speed in still water.