Question

Люди!!! Я надеюсь, что Вы не такие же тупые, как я... Вообщем прошу Вас , помогите с домашним заданием! Просто, как обычно первый день четверти и назадавали, как на год! №305 Два друга - охотника вышли навстречу друг другу из леса с двух сторон поляны и оказались на расстоянии 450 м друг от друга. Один шел со скоростью 70 м/мин, другой - 80 м/мин. Собака одного из охотников побежала навстречу другому. Добежав до него, она вернулась к хозяину и, повернув, снова бросилась к его другу. Так она продолжала свой бег до встречи двух охотников. Определите, какое расстояние пробежала собака, если она бегала со скоростью 12 км/ч. ПРОШУ С ОБЪЯСНЕНИЯМИ И ЧЕРТЕЖ!!!

Answer 1

70+80=150 м/мин совместная скорость или скорость сближения
450:150=3 мин через такое время они встретятся
3 мин= 3/60=1/20 ч
и столько же времени бегала собака, то есть всего она пробежала:
1/20 *12 =12/20=0,6 км=600 м

Answer 2

Problem Analysis

We are given that two friends, who are hunters, start walking towards each other from opposite sides of a clearing. They are initially 450 meters apart. One hunter walks at a speed of 70 m/min, while the other walks at a speed of 80 m/min. A dog belonging to one of the hunters runs towards the other hunter, reaches him, turns back, and runs towards the first hunter. The dog continues this pattern until the two hunters meet. We need to determine the distance the dog ran if it was running at a speed of 12 km/h.

Solution

To solve this problem, we can use the concept of relative speed. The relative speed between the two hunters is the sum of their individual speeds. In this case, the relative speed is 70 m/min + 80 m/min = 150 m/min.

Let's assume that the dog runs for t minutes before the two hunters meet. During this time, the dog covers a distance of 12 km/h * (t/60) h = (12/60) * t km = (1/5) * t km.

Since the relative speed between the two hunters is 150 m/min, the distance between them decreases by 150 m every minute. Therefore, the total time it takes for the two hunters to meet is 450 m / 150 m/min = 3 minutes.

Now, we can set up an equation to solve for t: (1/5) * t = 3

Simplifying the equation, we get: t = 15 minutes

Therefore, the dog ran a distance of (1/5) * 15 km = 3 km.

Answer

The dog ran a distance of 3 kilometers.

Explanation

The dog ran for 15 minutes at a speed of 12 km/h. Since the dog's speed is given in kilometers per hour, we need to convert the time from minutes to hours by dividing by 60. The distance covered by the dog is equal to the product of the speed and time, which is (12/60) * 15 = 3 km.

Diagram

Here is a diagram to help visualize the situation:

   Hunter A (70 m/min)          Hunter B (80 m/min)
   ----------------- 450 m -------------------
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   --------------------------------------------
                          Dog (12 km/h)

Note: The diagram is not to scale and is only intended to illustrate the relative positions of the hunters and the dog.