Question

Лена пригласила Ваню на день рождения. От дома Вани к дому Лены ведет две дороги, короткая1,6 км и длинная – 3,6 км. Ваня вы-шел из дома пораньше и пошел по длинной дороге, планируя появитьсятам точно в назначенный срок. Однако, пройдя две трети пути, Ваня об-наружил, что забыл дома смартфон и побежал за ним. Забежав домой,он продолжил бежать уже по короткой дороге. С какой скоростью шелВаня сначала, если он бежит вдвое быстрее, чем идет, и известно, что онприбежал, опоздав на пятнадцать минут?​

Answer 1

Ответ:2,4 км/ч

Объяснение:бежит- 2

Идёт-1

2,4:1=2,4км/ч- идёт

Answer 2

To solve this problem, let's break it down step by step.

Given Information:

- Distance from Vanya's house to Lena's house: - Short road: 1.6 km - Long road: 3.6 km - Vanya walks twice as fast as he runs. - Vanya arrived 15 minutes late.

Step 1: Calculate the time it takes for Vanya to walk the long road.

Let's assume that Vanya walks at a speed of x km/h. Since the distance is 3.6 km, the time it takes for Vanya to walk the long road is given by the formula:

Time = Distance / Speed

So, the time it takes for Vanya to walk the long road is:

Time_long_road = 3.6 / x

Step 2: Calculate the time it takes for Vanya to run the short road.

Since Vanya walks twice as fast as he runs, his running speed is x/2 km/h. The distance is 1.6 km, so the time it takes for Vanya to run the short road is:

Time_short_road = 1.6 / (x/2) = 3.2 / x

Step 3: Calculate the total time Vanya spent on both roads.

Vanya walked two-thirds of the long road before realizing he forgot his smartphone. This means he walked a distance of 2/3 * 3.6 = 2.4 km. The time it took for Vanya to walk this distance is:

Time_walked = 2.4 / x

After going back home to get his smartphone, Vanya ran the remaining distance of the long road, which is 3.6 - 2.4 = 1.2 km. The time it took for Vanya to run this distance is:

Time_run = 1.2 / (x/2) = 2.4 / x

The total time Vanya spent on both roads is the sum of the time he walked and the time he ran:

Total_time = Time_walked + Time_run = 2.4 / x + 2.4 / x = 4.8 / x

Step 4: Calculate the time Vanya was late.

We know that Vanya arrived 15 minutes late. Since the total time he spent on both roads is Total_time = 4.8 / x, we can set up the equation:

Total_time + 15/60 = Time_long_road

Substituting the values we calculated earlier:

4.8 / x + 15/60 = 3.6 / x

Now, let's solve this equation for x.

Solving the Equation:

To solve the equation, we can multiply both sides by x to eliminate the denominators:

4.8 + 15/60 * x = 3.6

Simplifying the equation:

4.8 + 0.25x = 3.6

Subtracting 4.8 from both sides:

0.25x = -1.2

Dividing both sides by 0.25:

x = -1.2 / 0.25 = -4.8

Since speed cannot be negative, we can conclude that there is no valid solution to this problem. Please double-check the given information and calculations to ensure accuracy.

If you have any further questions, feel free to ask!