Question

Грузовая машина проезжает расстояние между двумя городами за 20 часов,а легковая - за 10 часов.Машины одновременно выехали из этих городов навстречу друг другу.Через сколько часов они встретятся?

Answer 1

1/20 часть пути за 1 час проезжает грузовая машина
1/10 часть пути за 1 час проезжает легковая машина

1/20+1/10 = 1/20+2/20=3/20  части пути они проезжают вместе за 1 час

20/20:3/20=20/20*20/3=20/3=6 2/3 часа

Они встретятся через 6 2/3 часа

Answer 2

Problem Analysis

We are given that a truck travels a distance between two cities in 20 hours, while a car travels the same distance in 10 hours. Both vehicles start from their respective cities and travel towards each other. We need to determine how many hours it will take for them to meet.

Solution

To solve this problem, we can use the concept of relative speed. The relative speed between two objects moving towards each other is the sum of their individual speeds.

Let's assume the distance between the two cities is D.

The truck takes 20 hours to cover the distance, so its speed can be calculated as D/20.

Similarly, the car takes 10 hours to cover the distance, so its speed can be calculated as D/10.

When the truck and car are moving towards each other, their relative speed is the sum of their individual speeds:

Relative speed = (D/20) + (D/10)

To find the time it takes for them to meet, we can use the formula:

Time = Distance / Relative speed

Let's calculate the time it takes for them to meet:

Time = D / ((D/20) + (D/10))

Simplifying the equation:

Time = D / (3D/20)

Time = 20 / 3

Therefore, it will take 6.67 hours for the truck and car to meet.

Answer

The truck and car will meet after approximately 6.67 hours.

Note: The above calculation assumes constant speeds for both vehicles throughout the journey.