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divde the 12 balls into 3 sets of 4.
3 z& m6 H' n8 f: \! ?2 K" }tvb now,tvbnow,bttvbweight any 2 sets.) f9 a- C. s/ [8 V: h
if the 2 sets are equal, then you know the heavy one is in the thirdTVBNOW 含有熱門話題，最新最快電視，軟體，遊戲，電影，動漫及日常生活及興趣交流等資訊。/ @' E3 K! Q4 O; w  m$ x
if one of the 2 is heavier, then the heavy one is in that set
' y4 X6 D! F* V$ h公仔箱論壇then divide the 4 balls into 2.
, |4 W" k/ m% N% ^, n2 W" R. etvb now,tvbnow,bttvbweigh themtvb now,tvbnow,bttvb. T" Z! R7 \" k' o; U* u' ?
and divide the heavier into 1: ?1 Z8 Y; v  u+ N. x) z, S8 a# u
and weight them., y. f  n; S$ s
3 x weighing and get the ans.  
, L) {- Q- G, c+ R  X5 n' gin less than 15 secs.