標題:
數學題(Combination)#10 15分
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圖片參考：http://imgcld.yimg.com/8/n/HA00145646/o/701112150035113873411950.jpg ans:7a=20 b=10 c=70 8a=5 b=25 10a=9 b=6 請列出步驟,thanks 更新: 可唔可以解釋下第7題a BJ點解贏3場之中既6場去第7場 同c點解得出你所講既步驟
最佳解答:
7(a) As Blue Jays needs to win until 7 games, then the result of first six games should be 3-3 So, no. of ways = C(6,3) = 20 (b) As Expos needs to win until 6 games then the result of first five games should be 3-2 So, no. of ways = C(5,3) = 10 (c) Consider Blue Jays Wins in 4 games, 1 ways Wins in 5 games, 4 ways Wins in6 games, 10 ways (result of (b)) Wins in 7 games 20 ways (result of (a)) Total 35 ways Similarly for Expos Total possible ways = 2 * 35 = 70 10(a) 3 * 3 = 9 routes (b) 3 * 2 = 6 routes (As a man cannot use the rural roads for return)
其他解答:
7a. BJ should win the 7th game so only first 6 games will be consider in the series BJ should win 3 out of 6 games to get 7th game the combination is 6C3 = 20 7b. EX should win the 6th game so only first 5 games will be consider in the series EX should win 3 out of 5 games to get 7th game the combination is 5C3 = 10 7c. (consider BJ wins the series means BJ wins the lastmost game and so the games to be considered should be minus 1) in 4 games = 3C0 = 1 in 5 games = 4C1 = 4 in 6 games = 5C2 = 10 in 7 games = 6C3 = 20 as there are 2 teams, so the total combination of series = 2x(1+4+10+20) = 70 8. (what is the question?) 10a. routes from A to B = 3 routes from B to A = 3 so total routes from A to B and back to A = 3x3 = 9 10b. routes from B to A = 2 so total routes from A to B and back to A = 3x2 = 6 2011-12-16 22:59:53 補充： 7a. the 7th game will play only when each team wins 3 games 7c. e.g. BJ wins the series in 5 games 4 possible ways and you can realize BJ will get the last match: EX-BJ-BJ-BJ-BJ BJ-EX-BJ-BJ-BJ BJ-BJ-EX-BJ-BJ BJ-BJ-BJ-EX-BJ
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