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请教一道四年级补习数学题

2015-3-3 22:29| 发布者: karenbj | 查看: 1898| 原文链接

Patrick was running in a 500 m race. He ran 300 m in 50 seconds and walked the remaining distance. If he took 150 seconds in total to finish the race, what was his average speed?

Answer from school:
speed for 300 m = 300 ÷ 50 = 6 m/s
speed for remaining = 500-300=200
200 ÷ 100 = 2 m/s
therefore, (6+2) ÷ 2 = 4 m/s  (补习学校答案是4 m/s)

可是,我老公就是认为不对
他说应该用 500 ÷ 150 = 3.33 m/s

到底哪个对呢?我也迷糊晕了
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