Question

Скорый поезд вышел из Москвы в Санкт-Петербург и шел без остановок со скоростью 90 километров в час. Другой поезд вышел ему навстречу из Санкт-Петербурга в Москву и тоже шел без остановок со скоростью 70 километров в час. На каком расстоянии будут эти поезда за 15 минут до их встречи?

Answer 1

Поезда будут за 15 минут до встречи на 40 км друг от друга.
Ответ: 40 км

Answer 2

Problem Analysis

We are given two trains traveling towards each other without any stops. The first train is traveling from Moscow to St. Petersburg at a speed of 90 kilometers per hour, while the second train is traveling from St. Petersburg to Moscow at a speed of 70 kilometers per hour. We need to determine the distance between the two trains 15 minutes before they meet.

Solution

To find the distance between the two trains, we can calculate the distance traveled by each train in 15 minutes and then add them together.

Let's calculate the distance traveled by the first train in 15 minutes. We know that the first train is traveling at a speed of 90 kilometers per hour. To find the distance traveled in 15 minutes, we can use the formula:

Distance = Speed × Time

Converting 15 minutes to hours, we have:

Time = 15 minutes ÷ 60 minutes/hour = 0.25 hours

Substituting the values into the formula, we get:

Distance of the first train = 90 kilometers/hour × 0.25 hours = 22.5 kilometers

Now, let's calculate the distance traveled by the second train in 15 minutes. We know that the second train is traveling at a speed of 70 kilometers per hour. Using the same formula:

Distance = Speed × Time

Substituting the values, we get:

Distance of the second train = 70 kilometers/hour × 0.25 hours = 17.5 kilometers

Finally, we can find the total distance between the two trains by adding the distances traveled by each train:

Total distance = Distance of the first train + Distance of the second train = 22.5 kilometers + 17.5 kilometers = 40 kilometers

Therefore, the two trains will be 40 kilometers apart 15 minutes before they meet.

Answer

The two trains will be 40 kilometers apart 15 minutes before they meet.