Question

За 4 часа катер проходит по течению расстояние на 78 км большем,чем за 2 часа против течения.Какова скорость течения реки,если собственная скорость катера 30 км/ч.РЕШИТЕ ПЛИЗ!КТО РЕШИТ ОГРОМНОЕ СПАСИБО!)

Answer 1

30.5*0.2=6.1
30.5+6.1=36.6 км/ч (скорость теплохода)

Answer 2

Problem Analysis

We are given that a boat travels a distance 78 km greater in 4 hours with the current than in 2 hours against the current. We need to find the speed of the current.

Let's assume the speed of the boat in still water is B km/h and the speed of the current is C km/h.

Solution

To solve this problem, we can use the formula: Distance = Speed × Time.

Let's calculate the distance traveled by the boat in 4 hours with the current: Distance with current = (B + C) × 4.

And the distance traveled by the boat in 2 hours against the current: Distance against current = (B - C) × 2.

According to the problem statement, the distance with the current is 78 km greater than the distance against the current. So we can write the equation:

(B + C) × 4 = (B - C) × 2 + 78.

Now, let's solve this equation to find the value of C.

Calculation

Expanding the equation, we get: 4B + 4C = 2B - 2C + 78.

Simplifying the equation, we get: 2B + 6C = 78.

Rearranging the equation, we get: 2B = 78 - 6C.

Dividing both sides by 2, we get: B = (78 - 6C) / 2.

Now, we can substitute the value of B in terms of C into the equation B + C = 30 (given in the problem) to solve for C.

Substituting the value of B into the equation, we get: (78 - 6C) / 2 + C = 30.

Simplifying the equation, we get: 78 - 6C + 2C = 60.

Combining like terms, we get: -4C = -18.

Dividing both sides by -4, we get: C = 4.5.

Therefore, the speed of the current is 4.5 km/h.

Answer

The speed of the current is 4.5 km/h.

Explanation

The boat travels a distance 78 km greater in 4 hours with the current than in 2 hours against the current. This can be explained by the fact that when the boat is traveling with the current, the speed of the current adds to the speed of the boat, allowing it to cover more distance in the same amount of time. Conversely, when the boat is traveling against the current, the speed of the current subtracts from the speed of the boat, resulting in a slower speed and less distance covered in the same amount of time.

By solving the given equation, we found that the speed of the current is 4.5 km/h. This means that the current is flowing at a speed of 4.5 km/h in the opposite direction of the boat's motion.