Question

Катер за час проплыл 15 по течению реки и 4 км в стоячей воде .Скорость течения реки в 4 раза меньше скорости катера в стоячей воде Каков скорость тичения реки

Answer 1

Пусть $x$ км/ч - скорость течения, тогда $4x$ км/ч - скорость катера в стоячей воде.

Формула пути: $S= vt$ откуда $t= \frac{S}{v}$, значит:

$\frac{15}{4x+x} + \frac{4}{4x} =1|\cdot 5x\\ 15+5=5x\\ x=4$

Скорость катера в стоячей воде - 4 км/ч

Answer 2

Calculating the River's Current Speed

To calculate the speed of the river's current, we can use the given information about the boat's speed and distance traveled both with and against the current.

Given: - The boat traveled 15 km in the direction of the river's current in 1 hour. - The boat traveled 4 km against the river's current in 1 hour. - The speed of the river's current is 4 times slower than the speed of the boat in still water.

Let's denote the speed of the boat in still water as b and the speed of the river's current as r.

We can set up the following equations based on the given information:

1. The boat's speed with the current: b + r = 15. 2. The boat's speed against the current: b - r = 4. 3. The speed of the river's current is 4 times slower than the speed of the boat in still water: r = (1/4)b.

We can solve these equations to find the speed of the river's current.

Solving the Equations

We can solve the system of equations using the substitution method or the elimination method. Let's use the substitution method.

From equation 2, we have b = r + 4. We can substitute this expression for b into equation 1.

Substituting b = r + 4 into equation 1 gives: (r + 4) + r = 15.

Solving for r: 2r + 4 = 15, 2r = 15 - 4, 2r = 11, r = 11 / 2, r = 5.5.

Answer

The speed of the river's current is 5.5 km/h.