Question

человек полпути проехал на велосипеде со скоростью 25 км/ч , а остаток пути прошел со скоростью 5 км/ч . Сколько времени он шел , если весь путь занял 3ч ???

Answer 1

Полпути - это половина расстояния, а не половина времени.

$V_1=25$ км/ч

$V_2=5$ км/ч

$t=t_1+t_2=3$  часа

$S_1=S_2=0,5S$

$t_2=?$

$V_1t_1=V_2t_2$

$V_1(t-t_2)=V_2t_2$

 

$25(3-t_2)=5t_2$

$75-25t_2=5t_2$

$30t_2=75$

$t_2=75:30$

$t_2=2,5$ (ч.)

Ответ: человек шёл 2,5 часа.

Answer 2

Problem Analysis

A person traveled half of the distance on a bicycle at a speed of 25 km/h and the remaining distance at a speed of 5 km/h. The total time taken for the entire journey was 3 hours. We need to calculate the time the person spent walking.

Solution

Let's assume the total distance traveled is D km. Since the person traveled half of the distance on a bicycle, the distance traveled on the bicycle is D/2 km. The remaining distance traveled on foot is also D/2 km.

We can calculate the time spent on the bicycle using the formula:

Time = Distance / Speed

The time spent on the bicycle is (D/2) / 25 hours.

The time spent walking is the remaining time after subtracting the time spent on the bicycle from the total time of 3 hours:

Time walking = Total time - Time on bicycle

Time walking = 3 - [(D/2) / 25]

Now, we can substitute the given values and solve for the time spent walking.

Calculation

Let's calculate the time spent walking using the given information.

Total time = 3 hours

Speed on bicycle = 25 km/h

Speed walking = 5 km/h

Time walking = 3 - [(D/2) / 25]

Answer

The person spent 3 - [(D/2) / 25] hours walking.

Please provide the value of D (total distance traveled) to calculate the exact time spent walking.