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Antworten 5678

 #2
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The numbers 1,2,3,4,5,6,7,8,9 are arranged in a list so that each number is either greater than all the numbers that come before it or is less than all the numbers that come before it. For example, 4,5,6,3,2,7,1,8,9 is one such list: notice that (for instance) the 6 is greater than all the numbers that come before it, and the 2 is less than all the numbers that come before it. How many such lists of the numbers 1,2,3,4,5,6,7,8,9 are possible? Be sure to include complete explanations with your answer, using complete sentences. Imagine you were going to show your solution to a classmate, and try to write your solution so that he or she could understand it without doing any extra work.

 

How many such lists of the numbers 1,2,3,4,5,6,7,8,9 are possible?

 

\(n=9\)

 

There are \(2^{n-1}=2^{9-1}=2^8 = 256\) lists possible.

 

See Pascal's Triangle: Sum in line \(n-1 = 9-1 = 8\)

\(= ( 1+8+28+56+70+56+28+8+1 ) = 2^8 = 256\)

 

Lists:

1. ( 1, 2, 3, 4, 5, 6, 7, 8, 9 ) \(\qquad ( 1 \text{ list start with } 1 )\)

 

2. ( 2, 1, 3, 4, 5, 6, 7, 8, 9 )
3. ( 2, 3, 1, 4, 5, 6, 7, 8, 9 )
4. ( 2, 3, 4, 1, 5, 6, 7, 8, 9 )
5. ( 2, 3, 4, 5, 1, 6, 7, 8, 9 )
6. ( 2, 3, 4, 5, 6, 1, 7, 8, 9 )
7. ( 2, 3, 4, 5, 6, 7, 1, 8, 9 )
8. ( 2, 3, 4, 5, 6, 7, 8, 1, 9 )
9. ( 2, 3, 4, 5, 6, 7, 8, 9, 1 ) \(\qquad ( 8 \text{ lists start with } 2 )\)

 

10. ( 3, 2, 1, 4, 5, 6, 7, 8, 9 )
11. ( 3, 2, 4, 1, 5, 6, 7, 8, 9 )
12. ( 3, 2, 4, 5, 1, 6, 7, 8, 9 )
13. ( 3, 2, 4, 5, 6, 1, 7, 8, 9 )
14. ( 3, 2, 4, 5, 6, 7, 1, 8, 9 )
15. ( 3, 2, 4, 5, 6, 7, 8, 1, 9 )
16. ( 3, 2, 4, 5, 6, 7, 8, 9, 1 )
17. ( 3, 4, 2, 1, 5, 6, 7, 8, 9 )
18. ( 3, 4, 2, 5, 1, 6, 7, 8, 9 )
19. ( 3, 4, 2, 5, 6, 1, 7, 8, 9 )
20. ( 3, 4, 2, 5, 6, 7, 1, 8, 9 )
21. ( 3, 4, 2, 5, 6, 7, 8, 1, 9 )
22. ( 3, 4, 2, 5, 6, 7, 8, 9, 1 )
23. ( 3, 4, 5, 2, 1, 6, 7, 8, 9 )
24. ( 3, 4, 5, 2, 6, 1, 7, 8, 9 )
25. ( 3, 4, 5, 2, 6, 7, 1, 8, 9 )
26. ( 3, 4, 5, 2, 6, 7, 8, 1, 9 )
27. ( 3, 4, 5, 2, 6, 7, 8, 9, 1 )
28. ( 3, 4, 5, 6, 2, 1, 7, 8, 9 )
29. ( 3, 4, 5, 6, 2, 7, 1, 8, 9 )
30. ( 3, 4, 5, 6, 2, 7, 8, 1, 9 )
31. ( 3, 4, 5, 6, 2, 7, 8, 9, 1 )
32. ( 3, 4, 5, 6, 7, 2, 1, 8, 9 )
33. ( 3, 4, 5, 6, 7, 2, 8, 1, 9 )
34. ( 3, 4, 5, 6, 7, 2, 8, 9, 1 )
35. ( 3, 4, 5, 6, 7, 8, 2, 1, 9 )
36. ( 3, 4, 5, 6, 7, 8, 2, 9, 1 )
37. ( 3, 4, 5, 6, 7, 8, 9, 2, 1 ) \(\qquad ( 28 \text{ lists start with } 3 )\)

 

38. ( 4, 3, 2, 1, 5, 6, 7, 8, 9 )
39. ( 4, 3, 2, 5, 1, 6, 7, 8, 9 )
40. ( 4, 3, 2, 5, 6, 1, 7, 8, 9 )
41. ( 4, 3, 2, 5, 6, 7, 1, 8, 9 )
42. ( 4, 3, 2, 5, 6, 7, 8, 1, 9 )
43. ( 4, 3, 2, 5, 6, 7, 8, 9, 1 )
44. ( 4, 3, 5, 2, 1, 6, 7, 8, 9 )
45. ( 4, 3, 5, 2, 6, 1, 7, 8, 9 )
46. ( 4, 3, 5, 2, 6, 7, 1, 8, 9 )
47. ( 4, 3, 5, 2, 6, 7, 8, 1, 9 )
48. ( 4, 3, 5, 2, 6, 7, 8, 9, 1 )
49. ( 4, 3, 5, 6, 2, 1, 7, 8, 9 )
50. ( 4, 3, 5, 6, 2, 7, 1, 8, 9 )
51. ( 4, 3, 5, 6, 2, 7, 8, 1, 9 )
52. ( 4, 3, 5, 6, 2, 7, 8, 9, 1 )
53. ( 4, 3, 5, 6, 7, 2, 1, 8, 9 )
54. ( 4, 3, 5, 6, 7, 2, 8, 1, 9 )
55. ( 4, 3, 5, 6, 7, 2, 8, 9, 1 )
56. ( 4, 3, 5, 6, 7, 8, 2, 1, 9 )
57. ( 4, 3, 5, 6, 7, 8, 2, 9, 1 )
58. ( 4, 3, 5, 6, 7, 8, 9, 2, 1 )
59. ( 4, 5, 3, 2, 1, 6, 7, 8, 9 )
60. ( 4, 5, 3, 2, 6, 1, 7, 8, 9 )
61. ( 4, 5, 3, 2, 6, 7, 1, 8, 9 )
62. ( 4, 5, 3, 2, 6, 7, 8, 1, 9 )
63. ( 4, 5, 3, 2, 6, 7, 8, 9, 1 )
64. ( 4, 5, 3, 6, 2, 1, 7, 8, 9 )
65. ( 4, 5, 3, 6, 2, 7, 1, 8, 9 )
66. ( 4, 5, 3, 6, 2, 7, 8, 1, 9 )
67. ( 4, 5, 3, 6, 2, 7, 8, 9, 1 )
68. ( 4, 5, 3, 6, 7, 2, 1, 8, 9 )
69. ( 4, 5, 3, 6, 7, 2, 8, 1, 9 )
70. ( 4, 5, 3, 6, 7, 2, 8, 9, 1 )
71. ( 4, 5, 3, 6, 7, 8, 2, 1, 9 )
72. ( 4, 5, 3, 6, 7, 8, 2, 9, 1 )
73. ( 4, 5, 3, 6, 7, 8, 9, 2, 1 )
74. ( 4, 5, 6, 3, 2, 1, 7, 8, 9 )
75. ( 4, 5, 6, 3, 2, 7, 1, 8, 9 )
76. ( 4, 5, 6, 3, 2, 7, 8, 1, 9 )
77. ( 4, 5, 6, 3, 2, 7, 8, 9, 1 )
78. ( 4, 5, 6, 3, 7, 2, 1, 8, 9 )
79. ( 4, 5, 6, 3, 7, 2, 8, 1, 9 )
80. ( 4, 5, 6, 3, 7, 2, 8, 9, 1 )
81. ( 4, 5, 6, 3, 7, 8, 2, 1, 9 )
82. ( 4, 5, 6, 3, 7, 8, 2, 9, 1 )
83. ( 4, 5, 6, 3, 7, 8, 9, 2, 1 )
84. ( 4, 5, 6, 7, 3, 2, 1, 8, 9 )
85. ( 4, 5, 6, 7, 3, 2, 8, 1, 9 )
86. ( 4, 5, 6, 7, 3, 2, 8, 9, 1 )
87. ( 4, 5, 6, 7, 3, 8, 2, 1, 9 )
88. ( 4, 5, 6, 7, 3, 8, 2, 9, 1 )
89. ( 4, 5, 6, 7, 3, 8, 9, 2, 1 )
90. ( 4, 5, 6, 7, 8, 3, 2, 1, 9 )
91. ( 4, 5, 6, 7, 8, 3, 2, 9, 1 )
92. ( 4, 5, 6, 7, 8, 3, 9, 2, 1 )
93. ( 4, 5, 6, 7, 8, 9, 3, 2, 1 ) \(\qquad ( 56 \text{ lists start with } 4 )\)

 

94. ( 5, 4, 3, 2, 1, 6, 7, 8, 9 )
95. ( 5, 4, 3, 2, 6, 1, 7, 8, 9 )
96. ( 5, 4, 3, 2, 6, 7, 1, 8, 9 )
97. ( 5, 4, 3, 2, 6, 7, 8, 1, 9 )
98. ( 5, 4, 3, 2, 6, 7, 8, 9, 1 )
99. ( 5, 4, 3, 6, 2, 1, 7, 8, 9 )
100. ( 5, 4, 3, 6, 2, 7, 1, 8, 9 )
101. ( 5, 4, 3, 6, 2, 7, 8, 1, 9 )
102. ( 5, 4, 3, 6, 2, 7, 8, 9, 1 )
103. ( 5, 4, 3, 6, 7, 2, 1, 8, 9 )
104. ( 5, 4, 3, 6, 7, 2, 8, 1, 9 )
105. ( 5, 4, 3, 6, 7, 2, 8, 9, 1 )
106. ( 5, 4, 3, 6, 7, 8, 2, 1, 9 )
107. ( 5, 4, 3, 6, 7, 8, 2, 9, 1 )
108. ( 5, 4, 3, 6, 7, 8, 9, 2, 1 )
109. ( 5, 4, 6, 3, 2, 1, 7, 8, 9 )
110. ( 5, 4, 6, 3, 2, 7, 1, 8, 9 )
111. ( 5, 4, 6, 3, 2, 7, 8, 1, 9 )
112. ( 5, 4, 6, 3, 2, 7, 8, 9, 1 )
113. ( 5, 4, 6, 3, 7, 2, 1, 8, 9 )
114. ( 5, 4, 6, 3, 7, 2, 8, 1, 9 )
115. ( 5, 4, 6, 3, 7, 2, 8, 9, 1 )
116. ( 5, 4, 6, 3, 7, 8, 2, 1, 9 )
117. ( 5, 4, 6, 3, 7, 8, 2, 9, 1 )
118. ( 5, 4, 6, 3, 7, 8, 9, 2, 1 )
119. ( 5, 4, 6, 7, 3, 2, 1, 8, 9 )
120. ( 5, 4, 6, 7, 3, 2, 8, 1, 9 )
121. ( 5, 4, 6, 7, 3, 2, 8, 9, 1 )
122. ( 5, 4, 6, 7, 3, 8, 2, 1, 9 )
123. ( 5, 4, 6, 7, 3, 8, 2, 9, 1 )
124. ( 5, 4, 6, 7, 3, 8, 9, 2, 1 )
125. ( 5, 4, 6, 7, 8, 3, 2, 1, 9 )
126. ( 5, 4, 6, 7, 8, 3, 2, 9, 1 )
127. ( 5, 4, 6, 7, 8, 3, 9, 2, 1 )
128. ( 5, 4, 6, 7, 8, 9, 3, 2, 1 )
129. ( 5, 6, 4, 3, 2, 1, 7, 8, 9 )
130. ( 5, 6, 4, 3, 2, 7, 1, 8, 9 )
131. ( 5, 6, 4, 3, 2, 7, 8, 1, 9 )
132. ( 5, 6, 4, 3, 2, 7, 8, 9, 1 )
133. ( 5, 6, 4, 3, 7, 2, 1, 8, 9 )
134. ( 5, 6, 4, 3, 7, 2, 8, 1, 9 )
135. ( 5, 6, 4, 3, 7, 2, 8, 9, 1 )
136. ( 5, 6, 4, 3, 7, 8, 2, 1, 9 )
137. ( 5, 6, 4, 3, 7, 8, 2, 9, 1 )
138. ( 5, 6, 4, 3, 7, 8, 9, 2, 1 )
139. ( 5, 6, 4, 7, 3, 2, 1, 8, 9 )
140. ( 5, 6, 4, 7, 3, 2, 8, 1, 9 )
141. ( 5, 6, 4, 7, 3, 2, 8, 9, 1 )
142. ( 5, 6, 4, 7, 3, 8, 2, 1, 9 )
143. ( 5, 6, 4, 7, 3, 8, 2, 9, 1 )
144. ( 5, 6, 4, 7, 3, 8, 9, 2, 1 )
145. ( 5, 6, 4, 7, 8, 3, 2, 1, 9 )
146. ( 5, 6, 4, 7, 8, 3, 2, 9, 1 )
147. ( 5, 6, 4, 7, 8, 3, 9, 2, 1 )
148. ( 5, 6, 4, 7, 8, 9, 3, 2, 1 )
149. ( 5, 6, 7, 4, 3, 2, 1, 8, 9 )
150. ( 5, 6, 7, 4, 3, 2, 8, 1, 9 )
151. ( 5, 6, 7, 4, 3, 2, 8, 9, 1 )
152. ( 5, 6, 7, 4, 3, 8, 2, 1, 9 )
153. ( 5, 6, 7, 4, 3, 8, 2, 9, 1 )
154. ( 5, 6, 7, 4, 3, 8, 9, 2, 1 )
155. ( 5, 6, 7, 4, 8, 3, 2, 1, 9 )
156. ( 5, 6, 7, 4, 8, 3, 2, 9, 1 )
157. ( 5, 6, 7, 4, 8, 3, 9, 2, 1 )
158. ( 5, 6, 7, 4, 8, 9, 3, 2, 1 )
159. ( 5, 6, 7, 8, 4, 3, 2, 1, 9 )
160. ( 5, 6, 7, 8, 4, 3, 2, 9, 1 )
161. ( 5, 6, 7, 8, 4, 3, 9, 2, 1 )
162. ( 5, 6, 7, 8, 4, 9, 3, 2, 1 )
163. ( 5, 6, 7, 8, 9, 4, 3, 2, 1 ) \( \qquad ( 70 \text{ lists start with } 5 )\)

 

164. ( 6, 5, 4, 3, 2, 1, 7, 8, 9 )
165. ( 6, 5, 4, 3, 2, 7, 1, 8, 9 )
166. ( 6, 5, 4, 3, 2, 7, 8, 1, 9 )
167. ( 6, 5, 4, 3, 2, 7, 8, 9, 1 )
168. ( 6, 5, 4, 3, 7, 2, 1, 8, 9 )
169. ( 6, 5, 4, 3, 7, 2, 8, 1, 9 )
170. ( 6, 5, 4, 3, 7, 2, 8, 9, 1 )
171. ( 6, 5, 4, 3, 7, 8, 2, 1, 9 )
172. ( 6, 5, 4, 3, 7, 8, 2, 9, 1 )
173. ( 6, 5, 4, 3, 7, 8, 9, 2, 1 )
174. ( 6, 5, 4, 7, 3, 2, 1, 8, 9 )
175. ( 6, 5, 4, 7, 3, 2, 8, 1, 9 )
176. ( 6, 5, 4, 7, 3, 2, 8, 9, 1 )
177. ( 6, 5, 4, 7, 3, 8, 2, 1, 9 )
178. ( 6, 5, 4, 7, 3, 8, 2, 9, 1 )
179. ( 6, 5, 4, 7, 3, 8, 9, 2, 1 )
180. ( 6, 5, 4, 7, 8, 3, 2, 1, 9 )
181. ( 6, 5, 4, 7, 8, 3, 2, 9, 1 )
182. ( 6, 5, 4, 7, 8, 3, 9, 2, 1 )
183. ( 6, 5, 4, 7, 8, 9, 3, 2, 1 )
184. ( 6, 5, 7, 4, 3, 2, 1, 8, 9 )
185. ( 6, 5, 7, 4, 3, 2, 8, 1, 9 )
186. ( 6, 5, 7, 4, 3, 2, 8, 9, 1 )
187. ( 6, 5, 7, 4, 3, 8, 2, 1, 9 )
188. ( 6, 5, 7, 4, 3, 8, 2, 9, 1 )
189. ( 6, 5, 7, 4, 3, 8, 9, 2, 1 )
190. ( 6, 5, 7, 4, 8, 3, 2, 1, 9 )
191. ( 6, 5, 7, 4, 8, 3, 2, 9, 1 )
192. ( 6, 5, 7, 4, 8, 3, 9, 2, 1 )
193. ( 6, 5, 7, 4, 8, 9, 3, 2, 1 )
194. ( 6, 5, 7, 8, 4, 3, 2, 1, 9 )
195. ( 6, 5, 7, 8, 4, 3, 2, 9, 1 )
196. ( 6, 5, 7, 8, 4, 3, 9, 2, 1 )
197. ( 6, 5, 7, 8, 4, 9, 3, 2, 1 )
198. ( 6, 5, 7, 8, 9, 4, 3, 2, 1 )
199. ( 6, 7, 5, 4, 3, 2, 1, 8, 9 )
200. ( 6, 7, 5, 4, 3, 2, 8, 1, 9 )
201. ( 6, 7, 5, 4, 3, 2, 8, 9, 1 )
202. ( 6, 7, 5, 4, 3, 8, 2, 1, 9 )
203. ( 6, 7, 5, 4, 3, 8, 2, 9, 1 )
204. ( 6, 7, 5, 4, 3, 8, 9, 2, 1 )
205. ( 6, 7, 5, 4, 8, 3, 2, 1, 9 )
206. ( 6, 7, 5, 4, 8, 3, 2, 9, 1 )
207. ( 6, 7, 5, 4, 8, 3, 9, 2, 1 )
208. ( 6, 7, 5, 4, 8, 9, 3, 2, 1 )
209. ( 6, 7, 5, 8, 4, 3, 2, 1, 9 )
210. ( 6, 7, 5, 8, 4, 3, 2, 9, 1 )
211. ( 6, 7, 5, 8, 4, 3, 9, 2, 1 )
212. ( 6, 7, 5, 8, 4, 9, 3, 2, 1 )
213. ( 6, 7, 5, 8, 9, 4, 3, 2, 1 )
214. ( 6, 7, 8, 5, 4, 3, 2, 1, 9 )
215. ( 6, 7, 8, 5, 4, 3, 2, 9, 1 )
216. ( 6, 7, 8, 5, 4, 3, 9, 2, 1 )
217. ( 6, 7, 8, 5, 4, 9, 3, 2, 1 )
218. ( 6, 7, 8, 5, 9, 4, 3, 2, 1 )
219. ( 6, 7, 8, 9, 5, 4, 3, 2, 1 ) \(\qquad ( 56 \text{ lists start with } 6 )\)

 

220. ( 7, 6, 5, 4, 3, 2, 1, 8, 9 )
221. ( 7, 6, 5, 4, 3, 2, 8, 1, 9 )
222. ( 7, 6, 5, 4, 3, 2, 8, 9, 1 )
223. ( 7, 6, 5, 4, 3, 8, 2, 1, 9 )
224. ( 7, 6, 5, 4, 3, 8, 2, 9, 1 )
225. ( 7, 6, 5, 4, 3, 8, 9, 2, 1 )
226. ( 7, 6, 5, 4, 8, 3, 2, 1, 9 )
227. ( 7, 6, 5, 4, 8, 3, 2, 9, 1 )
228. ( 7, 6, 5, 4, 8, 3, 9, 2, 1 )
229. ( 7, 6, 5, 4, 8, 9, 3, 2, 1 )
230. ( 7, 6, 5, 8, 4, 3, 2, 1, 9 )
231. ( 7, 6, 5, 8, 4, 3, 2, 9, 1 )
232. ( 7, 6, 5, 8, 4, 3, 9, 2, 1 )
233. ( 7, 6, 5, 8, 4, 9, 3, 2, 1 )
234. ( 7, 6, 5, 8, 9, 4, 3, 2, 1 )
235. ( 7, 6, 8, 5, 4, 3, 2, 1, 9 )
236. ( 7, 6, 8, 5, 4, 3, 2, 9, 1 )
237. ( 7, 6, 8, 5, 4, 3, 9, 2, 1 )
238. ( 7, 6, 8, 5, 4, 9, 3, 2, 1 )
239. ( 7, 6, 8, 5, 9, 4, 3, 2, 1 )
240. ( 7, 6, 8, 9, 5, 4, 3, 2, 1 )
241. ( 7, 8, 6, 5, 4, 3, 2, 1, 9 )
242. ( 7, 8, 6, 5, 4, 3, 2, 9, 1 )
243. ( 7, 8, 6, 5, 4, 3, 9, 2, 1 )
244. ( 7, 8, 6, 5, 4, 9, 3, 2, 1 )
245. ( 7, 8, 6, 5, 9, 4, 3, 2, 1 )
246. ( 7, 8, 6, 9, 5, 4, 3, 2, 1 )
247. ( 7, 8, 9, 6, 5, 4, 3, 2, 1 ) \(\qquad ( 28 \text{ lists start with } 7 )\)

 

248. ( 8, 7, 6, 5, 4, 3, 2, 1, 9 )
249. ( 8, 7, 6, 5, 4, 3, 2, 9, 1 )
250. ( 8, 7, 6, 5, 4, 3, 9, 2, 1 )
251. ( 8, 7, 6, 5, 4, 9, 3, 2, 1 )
252. ( 8, 7, 6, 5, 9, 4, 3, 2, 1 )
253. ( 8, 7, 6, 9, 5, 4, 3, 2, 1 )
254. ( 8, 7, 9, 6, 5, 4, 3, 2, 1 )
255. ( 8, 9, 7, 6, 5, 4, 3, 2, 1 ) \(\qquad ( 8 \text{ lists start with } 8 )\)

 

256. ( 9, 8, 7, 6, 5, 4, 3, 2, 1 ) \(\qquad ( 1 \text{ list start with } 9 )\)

 

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07.03.2016