Question

Решите задачи с помощью уравнения. Собственная скорость теплохода в 9 раз больше, чем скорость течения реки. Плыви по течению, Теплоход проходит 45 км за 1 час 15 минут. Найдите скорость теплохода против течения?

Answer 1

1) 1) 45:1,25=36 (км/ч) скорость теплохода по течению2) х (км/ч) - скорость течения    9х (км/ч) - собственная скорость теплохода    х+9х=36     10х=36      х=3,6 (км/ч) - скорость течения     9*3,6 = 32,4 (км/ч) - собственная скорость теплохода3) 32,4-3,6=28,8 (км/ч) - скорость теплохода против течения

Answer 2

Problem Analysis

To solve this problem, we can use the formula for the speed of a boat in still water and the speed of the current. The formula is:

Boat's speed in still water = (Speed downstream + Speed upstream) / 2 Speed of the current = (Speed downstream - Speed upstream) / 2

Given that the boat's speed is 9 times greater than the speed of the current, and the boat travels 45 km downstream in 1 hour 15 minutes, we can use this information to find the boat's speed in still water and the speed of the current.

Solution

Let's denote: - B as the boat's speed in still water - C as the speed of the current

Given: - B = 9C - The boat travels 45 km downstream in 1 hour 15 minutes, which is 1.25 hours.

Using the formula: Boat's speed in still water = (Speed downstream + Speed upstream) / 2 Speed of the current = (Speed downstream - Speed upstream) / 2

We can calculate the boat's speed in still water and the speed of the current.

Boat's Speed in Still Water

The boat's speed downstream is 45 km in 1.25 hours, which is 36 km/h.

Boat's speed downstream = 45 km / 1.25 h = 36 km/h

The boat's speed upstream can be calculated using the boat's speed in still water and the speed of the current: B - C = 36 km/h B = 9C

Substitute the value of B from the second equation into the first equation: 9C - C = 36 km/h 8C = 36 km/h C = 36 km/h / 8 C = 4.5 km/h

Now, we can find the boat's speed in still water: B = 9C B = 9 * 4.5 km/h B = 40.5 km/h

Answer

The speed of the boat in still water when traveling upstream is 40.5 km/h.