put 3 balls on each side, 7 B0 G% w( n; D' G9 `$ A" y
if balance, we can prove that all 6 balls on the 天平 is normal,
: ^% L2 [ m8 D- Stvb now,tvbnow,bttvbif not balance, we can prove that the 6 balls outside the 天平 is normal.; A7 f& W+ @ a* ?
then use the proved-normal ball on one side and put the other ball on other side
" j+ d: K+ v7 D$ I, ~& o0 dto determine the abnormal is heavy and light |