The IQ of a Mob = (The lowest IQ in the Mob) / (The size of the Mob) This from a Terry Pratchett book. Can't remember which one, but it's one of the earlier Di

The IQ of a Mob = (The lowest IQ in the Mob) / (The size of the Mob) This from a Terry Pratchett book. Can't remember which one, but it's one of the earlier Discworld books.