The speed of a car going up the mountain from a to B is 30km / h, and the speed going down the mountain is 42km / h. find the average speed of the car going up and down the mountain

The speed of a car going up the mountain from a to B is 30km / h, and the speed going down the mountain is 42km / h. find the average speed of the car going up and down the mountain

The speed ratio of going up and down the mountain is 30:42 = 5:7
The time ratio of going up and down the mountain is 7:5
7 / (7 + 5) = 7 / 12
Downhill time accounts for 1-7 / 12 = 5 / 12 of the total
The average speed is: 30 × 7 / 12 + 42 × 5 / 12 = 35 km / h

The speed of the car up the mountain is 15 km / h and down the mountain is 30 km / h. The average speed up and down the mountain is ()

Suppose the downhill time is t, then the uphill time is 2T
The total distance is: 2T × 15 + T × 30 = 60t
The time is 2T + T = 3T
So the average velocity: v = 60t / 3T,
=20km/h.
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The speed of a car going up the mountain is 30km / h, and the speed of a car going down the mountain is 60km / h. The average speed of a car going up and down the mountain is______ Kilometers

(1 × 2) △ 130 + 160) = 2 △ 120 = 2 × 20 = 40 (km) a: the average speed of a car going up and down the mountain is 40 km

A car can travel 20 kilometers an hour up the mountain and 30 kilometers an hour down the original road. What is the average speed of the car up and down the mountain?
Can you tell me the formula?

Take the total energy distance up and down the mountain as unit "1"
The time to go up the mountain is 1 / 20, and the time to go down the mountain is 1 / 30
Average speed = total distance △ total time
That is: (1 + 1) / (1 / 20 + 1 / 30) = 2 / (5 / 60) = 24 (km / h)

There is a mountain road. When a car goes up the mountain, it travels 30 kilometers per hour. When it comes back from the original road, it travels 50 kilometers per hour when it goes down the mountain?
There is a mountain road. When a car goes up the mountain, it travels 30 kilometers per hour. When it comes back from the original road, it travels 50 kilometers per hour when it goes down the mountain?

Average speed = 2 / (1 / 30 + 1 / 50) = 37.5 km / h