Question

Из города А в город В одновременно выехали два автомобиля: первый со скоростью 80 км/ч, а второй — со скоростью 60 км/ч. Через полчаса следом за ними выехал третий автомобиль. Найдите скорость третьего автомобиля, если известно, что с момента, когда он догнал второй автомобиль, до момента, когда он догнал первый автомобиль, прошёл 1 час 15 минут. Ответ дайте в км/ч.!!!!!! пожалуйста очень надо!!!!!!!!

Answer 1

Problem Analysis

We are given that two cars, Car A and Car B, start simultaneously from City A to City B. Car A has a speed of 80 km/h, and Car B has a speed of 60 km/h. After half an hour, a third car starts from City A and catches up with Car B after 1 hour and 15 minutes. We need to find the speed of the third car.

Solution

Let's assume the speed of the third car is x km/h.

To find the speed of the third car, we can use the formula: distance = speed × time.

Let's calculate the distances covered by each car: - Car A: distance = speed × time = 80 km/h × (1 hour + 45 minutes) = 80 km/h × (1.75 hours) = 140 km - Car B: distance = speed × time = 60 km/h × (1 hour + 15 minutes) = 60 km/h × (1.25 hours) = 75 km

Since the third car catches up with Car B after 1 hour and 15 minutes, it covers the same distance as Car B. Therefore, the distance covered by the third car is also 75 km.

Now, we can set up an equation to find the speed of the third car: 75 km = x km/h × (1 hour + 15 minutes)

To solve for x, we need to convert 1 hour and 15 minutes to hours: 1 hour + 15 minutes = 1.25 hours

Now, we can rewrite the equation as: 75 km = x km/h × 1.25 hours

To solve for x, we can divide both sides of the equation by 1.25 hours: 75 km / 1.25 hours = x km/h

Simplifying the equation, we find: x = 60 km/h

Therefore, the speed of the third car is 60 km/h.

Answer

The speed of the third car is 60 km/h.