Question

Теплоход от пути а до б проходит по течению за 3 часа а от б до а - за 4 часа. скорость течения 4,5 км/2. найти его скорость в стоячей воде Помогите пожалуйста.

Answer 1

Ответ: 31,5 км/час.

Объяснение: х- скорость теплохода в стоячей воде.

Скорость теплохода по течению будет: (x+4,5);

Скорость теплохода против течения будет: (x-4,5);

Растояние от а до в: (x+4,5)*3;

Растояние от а до в : (x-4,5)*4;

Имеем равенство: (x+4,5)*3=(x-4,5)*4;

                                 3x+13,5=4x-18;

                                   4x-3x=18+13,5;

                                     x=31,5.

Answer 2

Problem Analysis

We are given that a boat travels from point A to point B in 3 hours against a current and from point B to point A in 4 hours with the current. The speed of the current is given as 4.5 km/h. We need to find the speed of the boat in still water.

Solution

Let's assume the speed of the boat in still water is x km/h.

When the boat travels from point A to point B against the current, the effective speed is reduced by the speed of the current. So, the effective speed is (x - 4.5) km/h. The time taken to travel from A to B is 3 hours.

When the boat travels from point B to point A with the current, the effective speed is increased by the speed of the current. So, the effective speed is (x + 4.5) km/h. The time taken to travel from B to A is 4 hours.

We can use the formula speed = distance/time to find the distance traveled in each case.

From A to B: Distance = (x - 4.5) km/h * 3 hours

From B to A: Distance = (x + 4.5) km/h * 4 hours

Since the distance traveled in both cases is the same, we can equate the two distances and solve for x.

Calculation

Let's calculate the value of x.

Distance from A to B = Distance from B to A

(x - 4.5) km/h * 3 hours = (x + 4.5) km/h * 4 hours

Simplifying the equation:

3(x - 4.5) = 4(x + 4.5)

3x - 13.5 = 4x + 18

3x - 4x = 18 + 13.5

-x = 31.5

x = -31.5

Since speed cannot be negative, we discard the negative value.

The speed of the boat in still water is 31.5 km/h.

Answer

The speed of the boat in still water is 31.5 km/h.