is it correct?

來源: 於 2009-06-17 17:12:21 [舊帖] [給我悄悄話] 本文已被閱讀：次

use 4 people as an example, X, A, B, C

X is the one who does not know his seat, and first get on,

Then, the probability of B and C wrong is at least 1/2.