小明每天下午五点放学
- 时间：2020-05-29 14:21:57
- 分类：数学世界
- 阅读：163 次
小明每天下午五点放学时，爸爸总是从家开车按时到达学校接他回家，有一天学校提前一小时放学，小明自己步行回家，在途中遇见来接他的爸爸，结果比平时早二十分钟到家，问小明步行多少分钟遇见来接他的爸爸？
数学题解答：设小明步行x分钟遇到来接她的爸爸，小明速度为a，车速度为b，平常从学校到家需花时间为t。（方程解法由卖女孩的小火柴同学解答）
2ax=20b
ax=10b
所以10b=(x-40)b
x=50
答：小明步行50分钟遇到来接她的爸爸。
算术方法（喃喃絮语和开心糊涂两位老师）：爸爸还需要10分钟到学校，20÷2=10（分） 60-10=50（分），提早20分钟，意味着节省了10分钟的来回，即4:50遇见小明。推荐阅读：
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