Question

Скорость товарного поезда на 40 км/ч меньше скорости пассажирского . Товарный поезд за 7 часов проходит такой же путь как пассажирский за 4,2 часов . Найдите скорость товарного поезда

Answer 1

Пусть х(км/ч) - скорость товарного поезда, тогда х+40 (км/ч) - скорость пассажирского, 7*х (км)- проходит товарный поезд, (х+40)*4,2 (км) - проходит пассажирский. По условию задачи оба поезда проходят один и тот же путь. Составим уравнение:
7х = (х+40)*4,2
7х = 4,2х + 168
7х - 4,2х = 168
2,8х = 168
х = 168:2,8
х = 60 (км/ч) - скорость товарного поезда
х+40 = 60+40 = 100 (км/ч) -скорость пассажирского поезда

Answer 2

Problem Analysis

We are given that the speed of a freight train is 40 km/h less than the speed of a passenger train. The freight train takes 7 hours to travel the same distance that the passenger train covers in 4.2 hours. We need to find the speed of the freight train.

Solution

Let's assume the speed of the passenger train is x km/h. According to the problem, the speed of the freight train is 40 km/h less than the speed of the passenger train, so the speed of the freight train is x - 40 km/h.

We know that distance = speed × time.

For the passenger train, the distance is the same as the freight train, and the time for the passenger train is 4.2 hours. So we have the equation:

Distance = Speed × Time

For the passenger train: Distance = x × 4.2

For the freight train: Distance = (x - 40) × 7

Since the distances are the same, we can equate the two equations:

x × 4.2 = (x - 40) × 7

Now we can solve this equation to find the value of x, which is the speed of the passenger train.