1) An ordinary deck of 52 playing cards is randomly divided into 4 piles of
13 cards each. Compute the probability that each pile has exactly 1 Ace
and 1 King?
2) How many 8-digit numbers are odd and have “4” in the hundreds place ?
Assume that a number does not begin with“0”.
.
Probability
2015-02-12 6:44 am
回答 (2)
2015-02-12 8:06 am
✔ 最佳答案
1)(13C1 × 12C1)⁴──────────
52C4 × 48C4
= 1265472 / 112559125 = 0.01124273132...
2)Method 1:
9 × 10 × 10 × 10 × 10 × 1 × 10 × 5
= 4500000 numbers.Method 2 :
(99999999 - 10000000 + 1) × 1/10 × 5/10
= 4500000 numbers.
2015-02-12 19:53:38 補充：
換換次序,是否恍然大悟?
(13C1)⁴ (12C1)⁴
───── × ─────
52C4 48C4
2015-02-12 19:56:32 補充：
比較下式,感觸良多!
(4C1)² (44C11) (3C1)² (33C11) (2C1)² (22C11) (1C1)² (11C11)
───────────────────────────────────────
(52C13) (39C13) (26C13) (13C13)
2015-02-12 5:51 pm
(13C1 × 12C1)⁴
──────────
52C4 × 48C4
神奇！請問 '雨後晴空' 老師，'分子代表什麼？分母又代表什麼呢？
──────────
52C4 × 48C4
神奇！請問 '雨後晴空' 老師，'分子代表什麼？分母又代表什麼呢？
收錄日期: 2021-04-21 22:31:09
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20150211000051KK00093