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| 送交者: 车五进二 2019月12月16日11:59:34 于 [灵机一动] 发送悄悄话 |
| 回 答: 趣味的数学-201 由 gugeren 于 2019-12-13 00:36:12 |
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In a lineup of 20 people, there are 19 possible spots where the B/G combination could exist, and each of those spot must have the same probability, multiply that probability with 19 will yield the expected value, or average number of the occurance of B/G in the lineup. |
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