Question

Из двух сёл,расстояние между которыми 20 км,одновременно вышли навстречу друг другу два пешехода и встретились через 2 часа после начала движения .Найдите скорость каждого пешехода,если известно,что первый пешеход проходит за 4 ч на 12 км больше чем второй за 3 часа

Answer 1

Расстояние, которое прошёл 1-й пешеход - S, расстояние, которое прошёл 2-й пешеход 20км - S, Используя формулу времени, т. е. , расстояние, делённое на скорость, находим время встречи пешеходов.
S / 3,5 + (20 - S ) / 4,5 = t, откуда t = (S + 20 - S ) / 8 = 20 / 8 = 2,5 часа

Answer 2

Problem Analysis

We are given that two pedestrians start walking towards each other from two villages that are 20 km apart. They meet each other 2 hours after the start of their journey. We need to find the speed of each pedestrian given that the first pedestrian covers 12 km more than the second pedestrian in 4 hours.

Solution

Let's assume the speed of the first pedestrian is x km/h and the speed of the second pedestrian is y km/h.

We know that the distance covered by the first pedestrian in 4 hours is 12 km more than the distance covered by the second pedestrian in 3 hours. Therefore, we can write the following equation:

4x = 3y + 12 We also know that the total distance between the two villages is 20 km, and they meet each other after 2 hours. Therefore, we can write the following equation:

2x + 2y = 20 Now we have a system of two equations with two variables. We can solve this system to find the values of x and y.

Solving the System of Equations

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

Multiplying equation by 2, we get:

4x + 4y = 40 Now we can subtract equation from equation:

(4x + 4y) - (4x) = 40 - (3y + 12)

4y - 3y = 40 - 12

y = 28

Substituting the value of y into equation we can find the value of x:

2x + 2(28) = 20

2x + 56 = 20

2x = -36

x = -18

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

Therefore, the speed of the first pedestrian is 18 km/h and the speed of the second pedestrian is 28 km/h.

Answer

The speed of the first pedestrian is 18 km/h and the speed of the second pedestrian is 28 km/h.