Question

Товарный поезд проезжает расстояние между двумя городами за 30ч. Однажды товарный и сккорый поезда выехали навстречу друг другу из этих городов и встретились через 12ч. За сколько часов скорый поезд проезжает расстояние между этими городами? НАПИШИТЕ РЕШЕНИЕ ЗАДАЧКИ

Answer 1

Если взять расстояние которое проезжает Тов.поезд за единицу(1), то составляем пропорцию:
30час.-1
12час-х
30:12=1:х
х=12:30
х=0,4
Теперь расстояние, которое проехал скорый поезд за 12 часов будет 1-0,4=0,6
Составляем пропорцию:
0,6-12час
1  - х часов
0,6:1=12:х
х=12:0,6
х=20 часов, за это время скорый поезд проедет расстояние между двумя городами.

Answer 2

Problem Analysis

We are given that a freight train travels a certain distance between two cities in 30 hours. On a certain day, a freight train and an express train depart from these cities towards each other and meet after 12 hours. We need to determine how long it takes for the express train to travel the distance between the cities.

Let's assume that the distance between the two cities is D and the speed of the freight train is F. We need to find the speed of the express train, which we'll call E.

Solution

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

We know that the freight train takes 30 hours to travel the distance between the cities, so its speed is given by: F = D / 30.

We also know that the freight train and the express train meet after 12 hours. During this time, the freight train has traveled a certain distance, and the express train has traveled the remaining distance. Let's call the distance traveled by the freight train D1 and the distance traveled by the express train D2.

Since the two trains are traveling towards each other, the sum of the distances traveled by both trains is equal to the total distance between the cities: D = D1 + D2.

We can also express the distances traveled by each train in terms of their speeds and the time it took for them to meet. The distance traveled by the freight train is given by: D1 = F * 12.

To find the distance traveled by the express train, we subtract the distance traveled by the freight train from the total distance: D2 = D - D1.

Now, we can express the speed of the express train in terms of the distance traveled by the express train and the time it took for them to meet: E = D2 / 12.

Substituting the values of D1 and D2 into the equation for E, we get: E = (D - F * 12) / 12.

Therefore, the express train takes (D - F * 12) / 12 hours to travel the distance between the cities.

Calculation

To calculate the time it takes for the express train to travel the distance between the cities, we need to know the values of D and F.

Unfortunately, the problem statement does not provide the values of D and F. Without this information, we cannot calculate the exact time it takes for the express train to travel the distance between the cities.

If you have the values of D and F, please provide them, and I will be happy to calculate the time for you.