Question

Поезд проехал 70 км. Первые 38 км он преодолевает за 50 минут, а остальные со средней скоростью 40 км. км/час. Рассчитайте среднюю скорость поезда на всем пути с точностью до км/ч.

Answer 1

Ответ:

Объяснение:

S = 70 км.

S1 =  38 км

t1 =  50 минут = 50/60 часа

V2 = 40 км/ч

Vc = ?

S2 = S - S1 = 70 - 38 = 32 км  второй участок пути

время на втором участке пути

t2 = S2/V2 = 32 / 40 ч

Общее время

t = t1+t2 = (50/60) + (32/40) = 196 / 120  ч.

средняя скорость на всем участке пути

Vc = S / t = 70*120 / 196 == 42,9 ==43 км/ч

Answer 2

Ответ:

43 км/ч

Решение:

Для того, что бы найти среднюю скорость, нужно найти весь путь, и поделить на все время.

1. Весь путь равен 70 км.

2. Все время:

а) 50 мин = 5/6 ч

б) 70 - 38 = 32 км — Оставшейся путь

32 : 40 = 0,8 ч - время преодоления 32 км

в) 5/6 + 0,8 = 5/6 + 4/5=25/30 + 24/30 =49/30 = 1    19/30

3. Средняя скорость

70:(49/30)=70*30/49=10*30/7=300/7=42 6/7  ≈ 43 км/ч

Answer 3

Problem Analysis

We are given that a train traveled a total distance of 70 km. The train covered the first 38 km in 50 minutes and the remaining distance at an average speed of 40 km/h. We need to calculate the average speed of the train for the entire journey.

Solution

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

Average Speed = Total Distance / Total Time

Let's calculate the total time taken by the train for the entire journey.

The train covered the first 38 km in 50 minutes. To convert minutes to hours, we divide by 60:

Time taken for the first 38 km = 50 minutes / 60 = 0.8333 hours

The remaining distance is 70 km - 38 km = 32 km. The train covered this distance at an average speed of 40 km/h. We can calculate the time taken for this distance using the formula:

Time = Distance / Speed

Time taken for the remaining 32 km = 32 km / 40 km/h = 0.8 hours

Now, we can calculate the total time taken for the entire journey:

Total Time = Time taken for the first 38 km + Time taken for the remaining 32 km

Total Time = 0.8333 hours + 0.8 hours = 1.6333 hours

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

Average Speed = Total Distance / Total Time

Average Speed = 70 km / 1.6333 hours ≈ 42.85 km/h

Therefore, the average speed of the train for the entire journey is approximately 42.85 km/h.

Answer

The average speed of the train for the entire journey is approximately 42.85 km/h.