Question

Поезд из пункта А в пункт В ехал со скоростью 60 км/ч, а обратно-со скоростью, меньшей на 20 км/ч. Какова его средняя скорость?

Answer 1

Пусть расстояние АВ равно х км, тогда из А в В поезд ехал x/60 ч, а из В в А x/20 ч. Его средняя скорость равна
$\frac{x+x}{\frac{x}{60}+\frac{x}{20}}=\\\\2x:\frac{x+3x}{60}=2x:\frac{4x}{60}=\frac{2x*60}{4x}=30$
ответ: 30 км\ч - средняя скорость

Answer 2

Calculation of Average Speed

To calculate the average speed of a train traveling from point A to point B and back, we need to consider the speeds of the train in both directions.

Let's denote the speed of the train from point A to point B as V1 (60 km/h) and the speed of the train from point B to point A as V2 (20 km/h less than V1).

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

Average Speed = Total Distance / Total Time

Since the train travels the same distance from point A to point B and back, the total distance is twice the distance between the two points.

Let's assume the distance between point A and point B is D.

The time taken to travel from point A to point B at a speed of V1 is given by:

Time1 = D / V1

The time taken to travel from point B to point A at a speed of V2 is given by:

Time2 = D / V2

The total time taken for the round trip is the sum of Time1 and Time2:

Total Time = Time1 + Time2

Now, we can substitute the values into the formula for average speed:

Average Speed = 2D / (Time1 + Time2)

Let's calculate the average speed using the given values.

Calculation:

Given: - Speed from point A to point B (V1) = 60 km/h - Speed from point B to point A (V2) = V1 - 20 km/h

To calculate the average speed, we need to know the distance between point A and point B (D). Unfortunately, the distance is not provided in the question. Without this information, we cannot calculate the average speed accurately.

Please provide the distance between point A and point B, and I will be happy to help you calculate the average speed.