题库搜索>问题求解PS-17738
建议使用官方纸质指南，查看对照完整题目
In the figure above, X and Y represent locations in a district of a certain city where the streets form a rectangular grid. In traveling only north or east along the streets from X to Y, how many different paths are possible?
分析A选项
分析B选项
分析C选项
分析D选项
分析E选项
我有更好的解析 
暂无雷哥网文字解析
从X到Y一共要走8步，其中3步是往北走的，5步是往东走的。可以简化成一个简单的组合问题，确定8步中哪3步是往北走的，就能计算出一共有多少种选择。
311475pmvj
8个空位子，往北是三个，往东是5个，把三个北放在8个位子里，问有多少种放法
0
0
回复
2022-09-18 12:04:19
680461elv
共八步，五步向左，三步向上，且选定任意一个方向的路线后，另一个方向相应的路线自动确定，所以求C（8，3）或者C（8，5）都可以
1
0
回复
2022-08-12 12:17:07
灭绝人性
没有人质疑一下 这题的选择 每一步的往东 往北 其实是固定的 先要到1 才可以到2？ 那么就没办法套用C（8.5） 因为必须按照 1 .2.3的顺序选择
0
0
回复
2022-06-26 04:15:45
努力滚动的绿猪猪
如果不知道这条规则，可以查一下Mississippi rule。
1
0
回复
2022-03-12 15:45:00
Crystal8
一共走八步，其中三步向上，五步向右‼️我是知道这个原理的，但是之前搞不清这样就可以用C3 8排列表示，现在明白了：共八步，给这八步分别命名为ABCDEFGH，这八个字母中有3个是
3
1
回复
2021-12-09 14:58:26
304247yrdh
C83
0
0
回复
2021-07-07 15:05:24
186871ad
这个题其实就是5个向右和3个向上的排列有多少种方式
3
0
回复
2021-06-07 01:17:24
186871ad
这个题其实就是5个
0
0
回复
2021-06-07 01:16:28
carpe diem
C（8，5）*C（3，3）=56
0
0
回复
2019-11-23 22:53:32
科目：
问题求解PS
来源：
难题300
题目信息2m4s
平均耗时
59.3%
平均正确率
该题由网友LyyCy9P提供
点击上传问题求解PS -18031
1-According to a recent theory, Archean-age gold-quartz vein systems were formed more than two...
问题求解PS -18029
吃撒程度
问题求解PS -18027
Let S be the set of all positive integers having at most 4 digits and such that each of the digits is 0 or 1 What is the greatest prime factor of the sum of all the numbers in S?
问题求解PS -17760
The addition problem above shows four of the 24 different integers that can be formed by using each of the digits 1, 2, 3, and 4 exactly once in each integer. What is the sum of these 24 integers?
问题求解PS -17738
In the figure above, X and Y represent locations in a district of a certain city where the streets form a rectangular grid. In traveling only north or east along the streets from X to Y, how many different paths are possible?
问题求解PS -18031
1-According to a recent theory, Archean-age gold-quartz vein systems were formed more than two...
问题求解PS -18029
吃撒程度
问题求解PS -18027
Let S be the set of all positive integers having at most 4 digits and such that each of the digits is 0 or 1 What is the greatest prime factor of the sum of all the numbers in S?
问题求解PS -17760
The addition problem above shows four of the 24 different integers that can be formed by using each of the digits 1, 2, 3, and 4 exactly once in each integer. What is the sum of these 24 integers?
问题求解PS -17738
In the figure above, X and Y represent locations in a district of a certain city where the streets form a rectangular grid. In traveling only north or east along the streets from X to Y, how many different paths are possible?
分享
周末、晚班滚动开班 
24+35+35+6课时 
