put 3 balls on each side,
y$ d' U, t& f; k. @/ U! {if balance, we can prove that all 6 balls on the 天平 is normal, 0 b$ K; U1 E1 b4 `" V" n
if not balance, we can prove that the 6 balls outside the 天平 is normal.5 M8 Z1 i4 H& b4 \
then use the proved-normal ball on one side and put the other ball on other side 5.39.217.76! w9 I, M B& Y5 t& o0 U' a
to determine the abnormal is heavy and light |