Question

Дорога из пункта А в пункт В состоит из спусков, подъемов и равнин. Велосипедист в гору поднимается со скоростью 11 км/ч, по равнине едет со скоростью 17 км/ч, а спускается 29 км/ч. Какая средняя скорость будет у велосипедиста, если он проехал из пункта А в В и обратно? Помогите!!! Это все условия.

Answer 1

17 км в час средняя сорость

Answer 2

Problem Analysis

The problem states that a cyclist travels from point A to point B and back, encountering uphill, flat, and downhill sections. The cyclist's speeds for each section are given: 11 km/h uphill, 17 km/h on flat ground, and 29 km/h downhill. We need to calculate the average speed of the cyclist for the entire round trip.

Solution

To calculate the average speed, we need to find the total distance traveled and the total time taken.

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

The time taken to travel uphill is D/11 hours, as the cyclist's speed is 11 km/h.

The time taken to travel on flat ground is D/17 hours, as the cyclist's speed is 17 km/h.

The time taken to travel downhill is D/29 hours, as the cyclist's speed is 29 km/h.

The total time taken for the round trip is (D/11) + (D/17) + (D/29) hours.

The total distance traveled for the round trip is 2D km.

The average speed is calculated by dividing the total distance by the total time:

Average Speed = Total Distance / Total Time

Average Speed = (2D) / ((D/11) + (D/17) + (D/29))

Simplifying the equation:

Average Speed = (2D) / ((29D + 17D + 11D) / (11 * 17 * 29))

Average Speed = (2 * 11 * 17 * 29) / (29 + 17 + 11)

Now we can calculate the average speed using the given values.

Calculation

Let's calculate the average speed:

Average Speed = (2 * 11 * 17 * 29) / (29 + 17 + 11)

Average Speed ≈ 17.94 km/h

Therefore, the average speed of the cyclist for the round trip from point A to point B and back is approximately 17.94 km/h.

Answer

The average speed of the cyclist for the round trip from point A to point B and back is approximately 17.94 km/h.

Note: The above calculation assumes that the uphill, flat, and downhill sections are of equal distance. If the distances of these sections are different, the calculation will be more complex.