Question

Сережа ехал на велосипеде 3 часа . за 1 час он проехал 5 часть всего пути , за 2 час половину оставшегося пути а в 3 час оставшиеся 12 км. какова длина всего пути ?

Answer 1

 За 1ый час велосипедист проехал пятую часть пути, т.е. осталось проехать еще четыре пятых.
 За 2ой час он проехал половину оставшегося пути, т.е. половину от четырех пятых, что равно двум пятым.
 За третий час он проехал оставшиеся две пятые пути, что равно 12 км. 
 Выходит, что 2/5 пути = 12 км; тогда 1/5 пути равна 6 км, а весь путь равен 6*5=30 км.

Answer 2

Problem Analysis

We are given that Sergey rode his bicycle for 3 hours. In the first hour, he covered 1/5th of the total distance. In the second hour, he covered half of the remaining distance. And in the third hour, he covered the remaining 12 km. We need to find the total length of the entire journey.

Solution

Let's assume the total distance Sergey traveled is x km.

According to the given information: - In the first hour, Sergey covered 1/5th of the total distance, which is x/5 km. - In the second hour, Sergey covered half of the remaining distance. The remaining distance after the first hour is x - (x/5) = (4x/5) km. So, Sergey covered (4x/5)/2 = 2x/5 km in the second hour. - In the third hour, Sergey covered the remaining 12 km.

We can set up the following equation to solve for x:

(x/5) + (2x/5) + 12 = x

Simplifying the equation, we get:

(3x/5) + 12 = x

Multiplying both sides of the equation by 5 to eliminate the fraction, we get:

3x + 60 = 5x

Subtracting 3x from both sides of the equation, we get:

60 = 2x

Dividing both sides of the equation by 2, we get:

x = 30

Therefore, the total length of the entire journey is 30 km.

Answer

The total length of the entire journey is 30 km.