Question

Между городами А и В по железной дороге 710 км. Из А и В вышел поезд со скоростью 75 км/ч. Через 2 ч навстречу ему из В в А вышел другой поезд со скоростью 65 км/ч .Через сколько часов после выхода второго поезда они встретятся?

Answer 1

1)75*2=150 км прошёл первый поезд до выхода второго

2)710-150=560 км осталось пройти поездам до встречи

3)75+65=140 км/час скорость сближения поездов

4)560:140=4 часа

Answer 2

Problem Analysis

We are given that the distance between cities A and B is 710 km. A train leaves city A towards city B with a speed of 75 km/h. After 2 hours, another train leaves city B towards city A with a speed of 65 km/h. We need to determine how many hours it will take for the two trains to meet.

Solution

To solve this problem, we can use the concept of relative speed. The relative speed of the two trains is the sum of their individual speeds. Let's calculate the relative speed:

Relative speed = Speed of train A + Speed of train B

Relative speed = 75 km/h + 65 km/h = 140 km/h

Now, we can use the formula:

Time = Distance / Speed

Let's substitute the values:

Time = 710 km / 140 km/h

Time = 5.07 hours

Therefore, it will take approximately 5.07 hours for the two trains to meet.

Answer

The two trains will meet approximately 5.07 hours after the second train departs from city B.