put 3 balls on each side, www1.tvboxnow.com$ \; b, s i' E. M5 z9 P( j
if balance, we can prove that all 6 balls on the 天平 is normal, $ ^; y: q; F+ O( C2 s# r$ n
if not balance, we can prove that the 6 balls outside the 天平 is normal.
: P |! c5 c! T2 J/ jtvb now,tvbnow,bttvbthen use the proved-normal ball on one side and put the other ball on other side |* B; K P- n& J& }# P
to determine the abnormal is heavy and light |