put 3 balls on each side, 7 D4 }" N/ P: |' T3 ^
if balance, we can prove that all 6 balls on the 天平 is normal, , Y* E5 V$ o) z3 Y
if not balance, we can prove that the 6 balls outside the 天平 is normal.5.39.217.76; ^: ~4 Y; R$ N7 z( ~& a
then use the proved-normal ball on one side and put the other ball on other side tvb now,tvbnow,bttvb$ i' H4 I9 o7 w" E7 q, Y) k) A
to determine the abnormal is heavy and light |