Question

Пожалуйста 2 способа.Даю 99 балов! Автомобиль проехал первую часть пути за 1,5ч со скоростью 84 км/ч,а вторую часть -за 2ч.С какой скоростью автомобиль проехал вторую часть пути, если средняя скорость на протяжении всего времени движения составляла 76 км/ч? Очень нужно!

Answer 1

НУ БЛИН ЩА Я ПОДУМАЮ И В КОМЕНТАХ НАПИШУ!

Answer 2

Solution 1: Using the Formula for Average Speed

To find the speed for the second part of the journey, we can use the formula for average speed, which is given by:

Average Speed = Total Distance / Total Time

Let's denote the distance for the first part of the journey as D1 and the distance for the second part of the journey as D2. The total distance is the sum of these two distances, i.e., D1 + D2. The total time is the sum of the time taken for the first part of the journey (1.5 hours) and the time taken for the second part of the journey (2 hours).

The average speed for the entire journey is given as 76 km/h. Using this information, we can set up an equation to solve for the speed of the second part of the journey.

Calculation:

Let's denote the speed for the second part of the journey as S2.

The distance for the first part of the journey (D1) = Speed * Time = 84 km/h * 1.5 h = 126 km The distance for the second part of the journey (D2) = Speed * Time = S2 * 2 h

Using the formula for average speed: Average Speed = Total Distance / Total Time 76 km/h = (D1 + D2) / (1.5 h + 2 h) 76 km/h = (126 km + S2 * 2 h) / 3.5 h Solving for S2, we get: S2 = (76 km/h * 3.5 h) - 126 km S2 = 266 km - 126 km S2 = 140 km/h

Therefore, the speed for the second part of the journey is 140 km/h.

[[4 #]]

Solution 2: Using the Harmonic Mean

Another method to find the speed for the second part of the journey is by using the harmonic mean. The harmonic mean is defined as the reciprocal of the arithmetic mean of the reciprocals of a set of numbers.

The formula for the harmonic mean is given by: Harmonic Mean = n / (1/x1 + 1/x2 + ... + 1/xn)

Where n is the number of values and x1, x2, ..., xn are the individual values.

In this case, we can use the harmonic mean to find the speed for the second part of the journey.

Calculation:

Let's denote the speed for the second part of the journey as S2.

Using the harmonic mean formula: Harmonic Mean = 2 / (1/84 + 1/S2) 76 = 2 / (1/84 + 1/S2) 76 = 2 / (0.0119 + 1/S2) 76 = 2 / (0.0119) + 2/S2 76 = 168.067 + 2/S2 -92.067 = 2/S2 S2 = 2 / -92.067 S2 ≈ -0.0217 km/h

Since the calculated speed for the second part of the journey is negative, it is not a valid solution. Therefore, the harmonic mean method does not provide a valid speed for the second part of the journey.

[[4 #]]