locmsimon asked in 科學及數學數學 · 9 years ago

數學題(Combination)#10 15分

圖片參考:http://imgcld.yimg.com/8/n/HA00145646/o/7011121500...

ans:7a=20 b=10 c=70 8a=5 b=25 10a=9 b=6

請列出步驟,thanks

Update:

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

2 Answers

Rating
  • ?
    Lv 7
    9 years ago
    Favorite Answer

    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)

  • ?
    Lv 5
    9 years ago

    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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