Question

Из пункта А в пункт В, расстояние между которыми 120 км, выехал автомобиль, а из пункта В в пункт А навстречу ему выехал велосипедист. через час они встретились. Через какое время с момента встречи расстояние между ними будет равно 40 км? Ответ дайте в минутах.

Answer 1

Т.к они встретились через час, то их общая скорость равна 120 км/ч.40 км это 1/3 всего пути значит надо 1 час *1/3=20 мин.Теперь 1 час(т.к они встретились через час) прибавить 20 мин=80мин.

Answer 2

Problem Analysis

We have an automobile and a cyclist traveling towards each other from point A to point B, which are 120 km apart. They meet after one hour. We need to determine how long it will take for the distance between them to be 40 km.

Solution

Let's assume the speed of the automobile is x km/h and the speed of the cyclist is y km/h.

We know that the total distance traveled by both the automobile and the cyclist is 120 km. Since they meet after one hour, we can set up the following equation:

x + y = 120 (Equation 1)

We also know that after some time, the distance between them will be 40 km. Let's assume it takes t hours for this to happen. The automobile will travel a distance of x * t km, and the cyclist will travel a distance of y * t km. We can set up the following equation:

x * t + y * t = 40 (Equation 2)

To solve this system of equations, we can use substitution or elimination. Let's use substitution.

From Equation 1, we can express x in terms of y:

x = 120 - y

Substituting this value of x into Equation 2, we get:

(120 - y) * t + y * t = 40

Simplifying the equation:

120t - yt + yt = 40

120t = 40

t = 40 / 120

t = 1/3 hours

To convert this to minutes, we multiply by 60:

t = (1/3) * 60

t = 20 minutes

Therefore, it will take 20 minutes from the time they meet for the distance between them to be 40 km.

Answer

The time it will take for the distance between the automobile and the cyclist to be 40 km after they meet is 20 minutes.