Question

Мальчик проехал половину пути со скоростью 16 км.ч половину оставшегося ВРЕМЕНИ он проехал со скоростью 12 км.ч затем до конца пути шел со скоростью 5 км.ч. Найти среднюю скорость мальчика

Answer 1

16+12+5:3=11
вот и всё

Answer 2

Problem Analysis

We are given the following information: - The boy traveled half of the distance at a speed of 16 km/h. - He traveled half of the remaining time at a speed of 12 km/h. - He walked the rest of the way at a speed of 5 km/h.

We need to find the average speed of the boy.

Solution

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

Let's assume that the total distance is D and the total time is T.

We can break down the problem into three parts:

1. The boy traveled half of the distance at a speed of 16 km/h. - Distance covered = D/2 - Time taken = (D/2) / 16 hours

2. The boy traveled half of the remaining time at a speed of 12 km/h. - Distance covered = (T - (D/2) / 2) * 12 km - Time taken = (T - (D/2)) / 2 hours

3. The boy walked the rest of the way at a speed of 5 km/h. - Distance covered = (D - (D/2) - ((T - (D/2)) / 2)) km - Time taken = (D - (D/2) - ((T - (D/2)) / 2)) / 5 hours

Now, we can calculate the total distance and total time:

- Total distance = D/2 + (T - (D/2)) / 2 + (D - (D/2) - ((T - (D/2)) / 2)) - Total time = (D/2) / 16 + (T - (D/2)) / 2 + (D - (D/2) - ((T - (D/2)) / 2)) / 5

Finally, we can calculate the average speed by dividing the total distance by the total time:

- Average speed = Total distance / Total time

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

Calculation

Let's assume the total distance D is 40 km and the total time T is 60 hours.

1. The boy traveled half of the distance at a speed of 16 km/h. - Distance covered = 40/2 = 20 km - Time taken = (20/16) hours = 1.25 hours

2. The boy traveled half of the remaining time at a speed of 12 km/h. - Distance covered = ((60 - (40/2)) / 2) * 12 = 10 km - Time taken = (60 - (40/2)) / 2 = 20 hours

3. The boy walked the rest of the way at a speed of 5 km/h. - Distance covered = (40 - (40/2) - ((60 - (40/2)) / 2)) = 10 km - Time taken = (40 - (40/2) - ((60 - (40/2)) / 2)) / 5 = 2 hours

Total distance = 20 + 10 + 10 = 40 km Total time = 1.25 + 20 + 2 = 23.25 hours

Average speed = Total distance / Total time = 40 / 23.25 ≈ 1.72 km/h

Therefore, the average speed of the boy is approximately 1.72 km/h.

Answer

The average speed of the boy is approximately 1.72 km/h.

Note: The given problem does not provide enough information to calculate the exact average speed. The above calculation is based on the assumption of a total distance of 40 km and a total time of 60 hours. The actual values may vary depending on the specific values provided in the problem.