Xiao Ming climbs up a high mountain and walks 4 kilometers an hour up the mountain and 6 kilometers an hour down the mountain to find the average speed up and down the mountain Walking 4 kilometers an hour up the mountain and 6 kilometers an hour down the mountain is the way back up the mountain

Xiao Ming climbs up a high mountain and walks 4 kilometers an hour up the mountain and 6 kilometers an hour down the mountain to find the average speed up and down the mountain Walking 4 kilometers an hour up the mountain and 6 kilometers an hour down the mountain is the way back up the mountain

Average speed = 2 ÷ (1 / 4 + 1 / 6) = 4.8 km / h

Xiaoming climbs the mountain. When he goes up the mountain, he walks 30 meters per minute. When he goes down the mountain, he goes back the same way. He walks 40 meters per minute. When Xiaoming goes up the mountain, his average speed is less than 30 meters per minute?
The wisdom garden for the second class of Statistics,

s/30=t1 s/40=t2
2s/(t1+t2)=2s*1200/(40s+30s)=34.3
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Xiaoming walks 40 meters per minute up the mountain and returns down the same road. Finally, the average speed of Xiaoming's going up and down the mountain is 48 meters per minute. How many meters does Xiaoming walk down the mountain per minute?

This problem can be solved by hypothesis
Analysis: the least common multiple of 40 and 48 is 240, so it can be assumed that the uphill journey is 120m
The time of going up and down the mountain is 120 △ 40 = 3 points; the total time of going up and down the mountain is 240 △ 48 = 5 points
Downhill time = 5-3 = 2 minutes,
Downhill speed = 120 △ 2 = 60m / min

How to improve the performance of 1000m in a short time?
Recently (about ten days) we will have a 1000 meter side race. I heard that the qualification standard is 4 minutes and 25 seconds. This morning, I went for a race, and the result is 4 minutes and 45 seconds. It doesn't meet the requirements, and it's 20 seconds slower. What's the effective way for me to improve my level in a week or so to meet the requirements?
Please be sure to have a practical and effective method, but don't mention doping and so on, and don't copy and paste the answers that are not consistent with this question!

Two aspects to enhance physical fitness, increase leg strength. Specific as follows. High kick in place, 30 on each side, 30 on each side. Try not to support the wall. Lunge squat, 30 on each side. Front and rear legs as far as possible, squat mainly feel the front stretch of the thigh of hind legs. Step jump, 30 on each side, find a higher than knee steps, such as the podium that