Question

из одного и того же пункта одновременно в протиположных направлениях вышли два пешехода.Через 3 ч расстояние между ними стало 21 км.найдите скорость второго пешехода,если скорость первого 4 км/ч

Answer 1

3 * 4 = 12 км прошел первый пешеход за 3 часа

21 - 12 = 9 км прошел второй пешеход за 3 часа

9 : 3 = 3 км/ч скорость второго пешехода.

Answer 2

4 км/ч - скорость 1-ого

х км/ч - скорость 2-ого

3 ч - время

21 км - расстояние

Уравнение:

3х+(3*4)=21

3х+12=21

3х=21-12

3х=9

х=3

Ответ: 3 км/ч - скорость вторгшо пешехода.

 

Answer 3

Problem Analysis

We are given that two pedestrians start walking simultaneously in opposite directions from the same point. After 3 hours, the distance between them is 21 km. We need to find the speed of the second pedestrian, given that the speed of the first pedestrian is 4 km/h.

Solution

Let's assume the speed of the second pedestrian is x km/h.

The distance covered by the first pedestrian in 3 hours is 4 km/h * 3 h = 12 km.

The distance covered by the second pedestrian in 3 hours is x km/h * 3 h = 3x km.

Since the total distance between them after 3 hours is 21 km, we can set up the equation:

12 km + 3x km = 21 km

Simplifying the equation:

3x km = 21 km - 12 km

3x km = 9 km

Dividing both sides of the equation by 3:

x km = 9 km / 3

x km = 3 km/h

Therefore, the speed of the second pedestrian is 3 km/h.

Answer

The speed of the second pedestrian is 3 km/h.