Question

Из одного города в другой выехал поезд .Первую половину расстояния он проехал за 2,4 часа со скоростью 72,75 км ч ,а вторую половину за 3,6 часа найти. Среднюю скорость поезда

Answer 1

V  ср. =   S общ. / t общ.
S общ.  - весь путь
t общ.  - время на прохождение всего пути

1) 72,75  * 2,4 = 174,6 (км) половина расстояния  (1/2)
2) 174,6  :  1/2  =  174,6 *2 = 349,2 (км) весь путь
3) 2,4 + 3,6 =  6 (ч.) время на прохождение всего пути
4) 349,2 : 6 = 58,2 (км/ч) средняя скорость

Ответ:  58,2 км/ч  средняя скорость поезда.

Answer 2

Problem Analysis

We are given that a train traveled from one city to another. The train took 2.4 hours to cover the first half of the distance at a speed of 72.75 km/h, and 3.6 hours to cover the second half of the distance. We need to find the average speed of the train.

Solution

To find the average speed of the train, we can use the formula:

Average Speed = Total Distance / Total Time

Let's calculate the total distance and total time traveled by the train.

Calculation

Let's assume the total distance traveled by the train is D.

The first half of the distance is covered in 2.4 hours at a speed of 72.75 km/h. Therefore, the distance covered in the first half is:

Distance1 = Speed1 * Time1

Distance1 = 72.75 km/h * 2.4 hours

The second half of the distance is covered in 3.6 hours. Therefore, the distance covered in the second half is:

Distance2 = Speed2 * Time2

We know that the first half and the second half of the distance are equal. Therefore, we can write:

Distance1 = Distance2

Substituting the values of Distance1 and Distance2, we get:

72.75 km/h * 2.4 hours = Speed2 * 3.6 hours

Now, we can solve this equation to find the value of Speed2.

Calculation Continued

Let's solve the equation:

72.75 km/h * 2.4 hours = Speed2 * 3.6 hours

Simplifying the equation:

173.4 km = Speed2 * 3.6 hours

Dividing both sides of the equation by 3.6 hours:

Speed2 = 173.4 km / 3.6 hours

Calculating the value of Speed2:

Speed2 = 48.17 km/h

Now that we have the value of Speed2, we can calculate the total distance traveled by the train:

Total Distance = Distance1 + Distance2

Total Distance = 72.75 km/h * 2.4 hours + 48.17 km/h * 3.6 hours

Calculating the value of Total Distance:

Total Distance = 174.6 km + 173.4 km

Total Distance = 348 km

Now, we can calculate the average speed of the train using the formula:

Average Speed = Total Distance / Total Time

The total time taken by the train is the sum of the time taken for the first half and the time taken for the second half:

Total Time = Time1 + Time2

Total Time = 2.4 hours + 3.6 hours

Calculating the value of Total Time:

Total Time = 6 hours

Finally, we can calculate the average speed of the train:

Average Speed = 348 km / 6 hours

Calculating the value of Average Speed:

Average Speed = 58 km/h

Answer

The average speed of the train is 58 km/h.

Conclusion

In this problem, we were given the time taken by a train to cover the first half and the second half of the distance, along with the speeds for each half. We used the formula for average speed to calculate the average speed of the train, which turned out to be 58 km/h.