Question

Из пункта А в пункт В автобус ехал со скоростью 90 км/ч.На обратном пути из-за непогоды он снизил скорость до 60 км/ч. Какова средняя скорость автобуса на все пути следования?

Answer 1

Обозначим расстояние между А и Б S

Тогда время, затраченное на туда и обратно

S/90 + S/60 = (2S+3S)/180 =

= 5S/180 = S/36

Общее расстояние туда и обратно 2S

Тогда средняя скорость

2S:S/36=2S×36/S = 72

Answer 2

Calculation of Average Speed

To calculate the average speed of the bus for the entire journey, we need to consider the distances traveled at different speeds.

Let's assume that the distance from point A to point B is the same as the distance from point B to point A.

Given: - Speed from point A to point B: 90 km/h - Speed from point B to point A: 60 km/h

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

Average Speed = Total Distance / Total Time

Since the distance is the same for both legs of the journey, we can simplify the formula to:

Average Speed = 2 * Distance / Total Time

To find the average speed, we need to know the total time taken for the entire journey.

Calculation of Total Time

To calculate the total time, we need to know the distance and the time taken for each leg of the journey.

Given: - Speed from point A to point B: 90 km/h - Speed from point B to point A: 60 km/h

Let's assume the distance from point A to point B is D.

The time taken from point A to point B can be calculated using the formula:

Time = Distance / Speed

Therefore, the time taken from point A to point B is:

Time from A to B = D / 90

Similarly, the time taken from point B to point A is:

Time from B to A = D / 60

The total time taken for the entire journey is the sum of the time taken for both legs:

Total Time = Time from A to B + Time from B to A

Substituting the values, we get:

Total Time = D / 90 + D / 60

Calculation of Average Speed (Continued)

Now that we have the total time, we can calculate the average speed using the formula:

Average Speed = 2 * Distance / Total Time

Substituting the value of the total time, we get:

Average Speed = 2 * D / (D / 90 + D / 60)

Simplifying the equation, we get:

Average Speed = 2 * D * (1 / 90 + 1 / 60)

To find the average speed, we need to know the distance between point A and point B. Unfortunately, the distance is not provided in the question. Without the distance, we cannot calculate the average speed.

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