Question

Теплоход проходит за 15 ч против течения столько же, сколько за 13 ч по течению. найдите скорость течения, если скорость теплохода 70 км/ч.

Answer 1

Х скорость течения
70+х скорость по течению
70-х против течения
13(70+х)=15(70-х)
910+13х=1050-15х
28х=140
х=5км/час скорость течения
Прямо супертеплоход с такой скоростью! 70км/час - круто!

Answer 2

Problem Analysis

We are given that a boat travels for 15 hours against the current and covers the same distance in 13 hours with the current. We need to find the speed of the current if the speed of the boat is 70 km/h.

Solution

Let's assume the speed of the current is x km/h.

When the boat is traveling against the current, its effective speed is the difference between the boat's speed and the current's speed. So, the effective speed is (70 - x) km/h.

When the boat is traveling with the current, its effective speed is the sum of the boat's speed and the current's speed. So, the effective speed is (70 + x) km/h.

We are given that the boat covers the same distance in both cases. Therefore, we can set up the following equation:

Distance = Speed × Time

For the boat traveling against the current: Distance = (70 - x) km/h × 15 h

For the boat traveling with the current: Distance = (70 + x) km/h × 13 h

Since the distances are the same, we can set up the equation:

(70 - x) × 15 = (70 + x) × 13

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

Calculation

Expanding the equation: 1050 - 15x = 910 + 13x

Combining like terms: -15x - 13x = 910 - 1050 -28x = -140 x = -140 / -28 x = 5

Answer

The speed of the current is 5 km/h.

Explanation

When the boat is traveling against the current, its effective speed is 70 km/h - 5 km/h = 65 km/h. In 15 hours, it covers a distance of 65 km/h × 15 h = 975 km.

When the boat is traveling with the current, its effective speed is 70 km/h + 5 km/h = 75 km/h. In 13 hours, it covers a distance of 75 km/h × 13 h = 975 km.

Therefore, the speed of the current is 5 km/h, and the boat covers a distance of 975 km in both cases.

References

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