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Xiaoyu and Xiaoli run in the 100 meter race, and each time Xiaoyu reaches the finish line 10 meters earlier than Xiaoli. If Xiaoyu goes back 10 meters to compete with Xiaoli, they start at the same time, and their average speed is the same as before, the result is () A. Xiao Li comes to the end first B. Xiao Yu comes to the end first C. go to the end together D. not sure
Let Xiaoyu use time t, then the speed is V1 = 100MT; Xiaoli use speed V2 = 100m − 10MT = 90mt; in the second competition, S1 ′ = 100m + 10m = 110m, S2 ′ = 100m, because the speed is not changed, Xiaoyu use time T1 = s ′ 1v1 = 110m100mt = 1110t; Xiaoli use time T2 = s ′ 2v2 = 100MT, 90mt = 109t; because 1110t < 109t; therefore, Xiaoyu reach the end first. So choose B
RELATED INFORMATIONS
- 1. Xiao Fang and Xiao Li collected 140 stamps, and Xiao Li's number is 2 / 5 of Xiao Fang's. how many stamps do they collect each? If you can, please ask elder brother and elder sister at 1:00
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- 3. In P.E. class, Xiaoming used to run 100 meters in 18 seconds, but now it only takes 15 seconds. What percentage has his speed increased?
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- 18. D is a point in the triangle ABC. Try to compare the size of AB + AC and BD + CD, and explain the reason
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