Question

Ваня вышел из дома в 8:00 и пошёл в школу. Он прошёл 400 метров со скоростью 4,5 км/ч и вспомнил, что забыл дома учебник. Мальчик пошёл обратно со скоростью 5 км/ч, дошёл до своей квартиры, взял учебник, побежал в школу со скоростью 7,22 км/ч. Успеет ли Петя дойти до школы и приготовиться к уроку, если до школы 1234 м, а урок начинается в 8:35. Петя тратит на приготовление к уроку 6 мин?​

Answer 1

Ответ:

Переведём 4,5 км/ч и 5 км/ч в м/мин

Делим расстояние на скорость,чтобы узнать,сколько потратил Ваня на первый выход и возвращение:

400/1,25=3,2 минуты

400/83,3=4,8 минуты

3,2+4,8=8 минут Ваня потратил на выход и возвращение

На часах 8:08

Переведем 7,22 км/ч=2м/мин

Делим расстояние до школы на скорость,чтобы узнать,за какое время Ваня дошёл до школы во второй раз:

1234/6,17=6 минут

в 8:14 он прибыл в школе+6 минут подготовки к уроку=8:20

у Вани в запасе ещё 15 минут

Answer 2

Problem Analysis

Vanya left home at 8:00 AM and walked to school. He walked 400 meters at a speed of 4.5 km/h and realized that he forgot his textbook at home. He then walked back at a speed of 5 km/h, reached his apartment, took the textbook, and ran to school at a speed of 7.22 km/h. The distance to the school is 1234 meters, and the lesson starts at 8:35 AM. Vanya spends 6 minutes preparing for the lesson. We need to determine if Vanya will reach the school on time and have enough time to prepare for the lesson.

Solution

To solve this problem, we need to calculate the time it takes for Vanya to walk to school, the time it takes for him to return home and get his textbook, and the time it takes for him to run to school. We will then compare the total time with the time available before the lesson starts.

Let's calculate the time it takes for Vanya to walk to school: - Distance: 400 meters - Speed: 4.5 km/h

To convert the speed from km/h to m/s, we divide it by 3.6: - Speed: 4.5 km/h ÷ 3.6 = 1.25 m/s

The time it takes to walk to school is calculated by dividing the distance by the speed: - Time: 400 meters ÷ 1.25 m/s = 320 seconds

Next, let's calculate the time it takes for Vanya to return home and get his textbook: - Distance: 400 meters - Speed: 5 km/h

Converting the speed to m/s: - Speed: 5 km/h ÷ 3.6 = 1.39 m/s

The time it takes to return home is: - Time: 400 meters ÷ 1.39 m/s = 287.77 seconds

Now, let's calculate the time it takes for Vanya to run to school: - Distance: 1234 meters - Speed: 7.22 km/h

Converting the speed to m/s: - Speed: 7.22 km/h ÷ 3.6 = 2.01 m/s

The time it takes to run to school is: - Time: 1234 meters ÷ 2.01 m/s = 613.93 seconds

Finally, let's calculate the total time: - Total time: Time to walk to school + Time to return home + Time to run to school + Time to prepare for the lesson

Converting the total time to minutes: - Total time: (320 + 287.77 + 613.93 + 6) seconds ÷ 60 = 26.53 minutes

Since the lesson starts at 8:35 AM and Vanya will take approximately 26.53 minutes, we can calculate the time he arrives at school: - Arrival time: 8:00 AM + 26.53 minutes = 8:26:32 AM

Therefore, Vanya will arrive at school at approximately 8:26:32 AM, which is before the lesson starts at 8:35 AM. He will have enough time to prepare for the lesson.

Note: The calculations provided above are based on the given information and assumptions. The actual time may vary depending on various factors.

Answer

Vanya will arrive at school at approximately 8:26:32 AM and will have enough time to prepare for the lesson before it starts at 8:35 AM.