Question

СОЧНО ДАЮ 35 БАЛЛОВ Расстояние между двумя пунктами по реке равно 80км.Это расстояние лодка проплывает по течению реки 5 ч ,а против течения - за 8 ч.Найдите собственную скорость лодки и скорость течения реки

Answer 1

Ответ:

80:5=16км/час скорость по течению

80:8=10км/час скорость против течения

(16-10):2=3км/час скорость течения

16-3=10+3=13км/час собственная скорость

Объяснение:

Answer 2

Problem Analysis

We are given the following information: - The distance between two points along a river is 80 km. - The boat takes 5 hours to travel this distance downstream (with the current). - The boat takes 8 hours to travel this distance upstream (against the current).

We need to find the speed of the boat and the speed of the current.

Solution

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

When the boat is traveling downstream, its effective speed is the sum of its own speed and the speed of the current. Therefore, the boat's effective speed is B + C km/h.

When the boat is traveling upstream, its effective speed is the difference between its own speed and the speed of the current. Therefore, the boat's effective speed is B - C km/h.

We can use the formula speed = distance / time to calculate the boat's speed in each scenario.

Calculating the Speed of the Boat

Given that the boat takes 5 hours to travel 80 km downstream, we can set up the equation:

B + C = 80 / 5

Simplifying the equation, we get:

B + C = 16 (Equation 1)

Similarly, given that the boat takes 8 hours to travel 80 km upstream, we can set up the equation:

B - C = 80 / 8

Simplifying the equation, we get:

B - C = 10 (Equation 2)

We now have a system of equations (Equation 1 and Equation 2) that we can solve to find the values of B and C.

Adding Equation 1 and Equation 2, we get:

(B + C) + (B - C) = 16 + 10

Simplifying the equation, we get:

2B = 26

Dividing both sides of the equation by 2, we get:

B = 13

Substituting the value of B into Equation 1, we get:

13 + C = 16

Simplifying the equation, we get:

C = 3

Therefore, the speed of the boat is 13 km/h and the speed of the current is 3 km/h.

Answer

The speed of the boat is 13 km/h and the speed of the current is 3 km/h.