Question

Лодка прошла вниз по реке 42 км, а затем 27 км против течения, затратив на весь путь 15 часов. Найти скорость течения реки, если скорость моторной лодки в стоячей воде равна 5 км/ч

Answer 1

Ответ:

см фото

Объяснение:

Answer 2

Calculating River Current Speed

To calculate the speed of the river's current, we can use the formula: Speed of the boat downstream = Speed of the boat in still water + Speed of the current and Speed of the boat upstream = Speed of the boat in still water - Speed of the current

Given: - Distance downstream = 42 km - Distance upstream = 27 km - Total time = 15 hours - Speed of the boat in still water = 5 km/h

We can set up the following equations based on the given information: 1. Downstream journey: - Speed of the boat downstream = 5 km/h + Speed of the current - Time taken downstream = Distance downstream / (5 km/h + Speed of the current) = 42 / (5 + Speed of the current)

2. Upstream journey: - Speed of the boat upstream = 5 km/h - Speed of the current - Time taken upstream = Distance upstream / (5 km/h - Speed of the current) = 27 / (5 - Speed of the current)

We also know that the total time taken for the entire journey is 15 hours: - Total time = Time downstream + Time upstream - 15 = 42 / (5 + Speed of the current) + 27 / (5 - Speed of the current)

Let's solve for the speed of the current using the given information.

Calculations

Using the given information and the equations set up, we can solve for the speed of the current.

First, we'll solve the equation: 15 = 42 / (5 + Speed of the current) + 27 / (5 - Speed of the current)

After solving the equation, we find that the speed of the current is approximately 3 km/h.

So, the speed of the river's current is 3 km/h.