Question 6
There are 21 medals:7 gold,7 silver and 7 bronze. Exactly one medal is defective. A defective gold medal is lighter than a genuine gold medal; a defective bronze medal is heavier than a genuine bronze medal; a defective silver medal may be lighter or heavier than a genuine silver medal. Genuine medals of the same metal have equal mass. Find the defective medal in three weighings on a balance scale without weights. (10 points)
Neutral editorial illustration.
Neutral editorial illustration.