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A car goes from place a to place B at the speed of 40 kilometers per hour. After arriving at place B, it returns to place a from the original road at the speed of 60 kilometers per hour. What is the average speed of this car?
A: the average speed of this car is 48 km / h
The speed of a car going up the mountain is 12 kilometers per hour. According to the speed of going down the mountain on the original road, it is 20 kilometers per hour. The average speed of going back and forth is 12 kilometers per hour______ Kilometers
Suppose the whole journey is 1, we can get: 1 × 2 △ 112 + 120 = 2 △ 215, = 15 (km / h). Answer: the average speed of round trip is 15 km / h.so the answer is: 15
When a car runs along a mountain road, it travels an average of 20 kilometers per hour up the mountain and 30 kilometers per hour down the mountain. Find the average speed of the car up and down the mountain
Hello, Jianbing
The total distance is "1" and the uphill time is:
1÷20＝1/20
The downhill time is:
1÷30＝1/30
The average speed up and down the mountain is per hour
(1 + 1) / (1 / 20 + 1 / 30) = 24 (km)
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