Question

Длина водохранилища на 200 км больше его ширины. поездка на катере с одинаковой скоростью через водохранилище по его длине занимает 30 ч., а по ширине 20 ч.. найди длину и ширину водохранилища.

Answer 1

длина больше ширины на 200 км и на поездку вдоль нее требует на 10 ч больше, чем по ширине. значит, катер за 10 ч проходит эти 200км. значит, за 1 час катер проходит 200/10=20км. получаем, что если на поездку по длине катеру надо 30ч, то длина = 30*20=600 км, а ширина 20*20=400 км. (или 600-200=400км)

Answer 2

Problem Analysis

We are given that the length of a reservoir is 200 km greater than its width. The time it takes to travel across the reservoir at a constant speed is 30 hours along the length and 20 hours along the width. We need to find the length and width of the reservoir.

Solution

Let's assume the width of the reservoir is x km. According to the given information, the length of the reservoir is 200 km greater than its width, so the length can be represented as x + 200 km.

We are also given that the time it takes to travel across the reservoir at a constant speed is 30 hours along the length and 20 hours along the width.

To find the speed, we can use the formula:

Speed = Distance / Time

Let's calculate the speed along the length and width:

Speed along the length = (x + 200) km / 30 hours

Speed along the width = x km / 20 hours

Since the speed remains constant, we can equate the two speeds:

(x + 200) km / 30 hours = x km / 20 hours

Now, let's solve this equation to find the value of x, which represents the width of the reservoir.

Calculation

To solve the equation, we can cross-multiply:

20(x + 200) = 30x

20x + 4000 = 30x

4000 = 30x - 20x

4000 = 10x

x = 400

Answer

The width of the reservoir is 400 km.

To find the length, we can substitute the value of x into the equation for the length:

Length = x + 200 = 400 + 200 = 600 km

Therefore, the length of the reservoir is 600 km.

Summary

The width of the reservoir is 400 km, and the length of the reservoir is 600 km.