put 3 balls on each side, 1 Z9 Y' W' e) H" E9 f/ [" y* D. v
if balance, we can prove that all 6 balls on the 天平 is normal, tvb now,tvbnow,bttvb$ B* D5 e! G8 F4 M! }7 F
if not balance, we can prove that the 6 balls outside the 天平 is normal.5.39.217.76* r8 i S$ J. h9 |- Y$ ~. n! `# N
then use the proved-normal ball on one side and put the other ball on other side
3 L6 s2 `2 i! C7 w3 l3 ?5.39.217.76to determine the abnormal is heavy and light |