Anonymous
Anonymous asked in 科學數學 · 1 decade ago

數學 Probability

Two cards are drawn from a standard deck of cards. Find probability : (both either black or an ace) .

please show work. Thanks.

Update:

Thanks golf, but they gave answer was 63/221. Can you try to figure out.

Update 2:

感謝golf 及釋塵 大師熱心解答. 經過請教一位 ABC 有關 (both either black or an ace ) 的原意. 她說其實翻譯成"兩張卡都只能為黑色或王牌, 較易了解.(通常我們翻譯成 不是.....就是.... ) 而且重點在 either black or an ace .也就是說, 可以是一張黑色及一張王牌(不限顏色). 我想, 這樣答案就對了. 我們都誤解為(both are black or both are aces) . Thanks again.

1 Answer

Rating
  • 釋塵
    Lv 7
    1 decade ago
    Favorite Answer

    都是黑色的機率 = C(26,2)/C(52,2) = 650/2652

    都是ace的機率 = C(4,2)/C(52,2) = 12/2652

    既是黑色又是ace的機率 = 1/C(52,2) = 2/2652

    由此可知both either black or an ace

    =(650+12-2)/2652

    =55/221……………(解答)

    ps:你的解答應該有錯!!

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