Question

Пешеход часть пути прошёл со скоростью 3 км/ч, затратив на это 2/3 времени своего движения. За оставшуюся треть времени он прошёл остальной путь со скоростью 6 км/ч. Определите среднюю скорость.

Answer 1

Дано: t1=2/3 , t2=1/, V1=3км/ч,V2=6км/ч. Найти ср.V=? Решение : Vср.=V1+V2/t. t=2/3+1/3=4/3=4.3 , Vcр.=3км/ч+6км/ч /4.3c =2.09км/ч Ответ : Vср.=2.09км/ч.
Наверное .

Answer 2

Problem Analysis

We are given that a pedestrian covers a certain distance with two different speeds. The pedestrian covers 2/3 of the distance with a speed of 3 km/h and the remaining 1/3 of the distance with a speed of 6 km/h. We need to determine the average speed of the pedestrian.

Solution

To find the average speed, we can use the formula:

Average Speed = Total Distance / Total Time

Let's assume the total distance covered by the pedestrian is D km.

The time taken to cover 2/3 of the distance at a speed of 3 km/h can be calculated using the formula:

Time = Distance / Speed

The time taken to cover the remaining 1/3 of the distance at a speed of 6 km/h can also be calculated using the same formula.

The total time taken by the pedestrian can be found by adding the two times calculated above.

Finally, we can substitute the values of the total distance and total time into the average speed formula to find the average speed.

Let's calculate the average speed step by step:

1. Let's assume the total distance covered by the pedestrian is D km. 2. The distance covered with a speed of 3 km/h is 2/3 of the total distance, which is (2/3) * D km. 3. The distance covered with a speed of 6 km/h is 1/3 of the total distance, which is (1/3) * D km. 4. The time taken to cover (2/3) * D km at a speed of 3 km/h is ((2/3) * D) / 3 hours. 5. The time taken to cover (1/3) * D km at a speed of 6 km/h is ((1/3) * D) / 6 hours. 6. The total time taken by the pedestrian is (((2/3) * D) / 3) + (((1/3) * D) / 6) hours. 7. The average speed is given by the formula: Average Speed = Total Distance / Total Time. - Substituting the values, Average Speed = D / ((((2/3) * D) / 3) + (((1/3) * D) / 6)) km/h.

Let's simplify the expression for the average speed:

1. Multiply the numerator and denominator by 6 to eliminate the fractions. - Average Speed = (6 * D) / ((((2/3) * D) / 3) * 6 + (((1/3) * D) / 6) * 6) km/h. - Simplifying further, Average Speed = (6 * D) / (((4/3) * D) + ((1/2) * D)) km/h. 2. Combine the fractions in the denominator. - Average Speed = (6 * D) / (((8/6) * D) + ((3/6) * D)) km/h. - Simplifying further, Average Speed = (6 * D) / ((11/6) * D) km/h. 3. Cancel out the common factor of D in the numerator and denominator. - Average Speed = 6 / (11/6) km/h. - Simplifying further, Average Speed = (6 * 6) / 11 km/h. - Average Speed = 36 / 11 km/h.

Therefore, the average speed of the pedestrian is 36/11 km/h.

Answer

The average speed of the pedestrian is 36/11 km/h.