Question

Скорость лодки по течению реки 18 км/ч, а против течения 15 км/ч.Найти собственную скорость лодки и скорость течения реки.

Answer 1

Пусть у собственная скорость лодки, а х скорость течения

у+х=18

у - х=15

2у=33

у=16,5км/ч собственная скорость лодки

18-16,5=1,5км/ч скорость течения реки

 

Вариант 2

18-15=3км/ч двойная скорость течения

3/2=1,5км/ч скорость течения реки

 

Answer 2

Problem Analysis

To find the speed of the boat and the speed of the river current, we can set up a system of equations based on the given information. Let's assume the speed of the boat is represented by b and the speed of the river current is represented by c. We can use the following equations:

1. Speed of the boat downstream (with the current): b + c = 18 km/h 2. Speed of the boat upstream (against the current): b - c = 15 km/h

We can solve this system of equations to find the values of b and c.

Solution

To solve the system of equations, we can use the method of substitution or elimination. Let's use the method of elimination:

Adding the two equations together, we get:

(b + c) + (b - c) = 18 + 15

Simplifying the equation, we get:

2b = 33

Dividing both sides of the equation by 2, we find:

b = 16.5 km/h

Now, we can substitute the value of b into one of the original equations to find the value of c. Let's use the first equation:

16.5 + c = 18

Subtracting 16.5 from both sides of the equation, we find:

c = 1.5 km/h

Therefore, the speed of the boat is 16.5 km/h and the speed of the river current is 1.5 km/h.

Answer

The speed of the boat is 16.5 km/h and the speed of the river current is 1.5 km/h.