Andrew Su, CEO at brokerage Compass Global Markets said the average cost of producing gold in Australia, home to some of the world's biggest gold miners, has jumped from $500 an ounce in 2007 to over $1,000 an ounce this year.
Persons (plural) is a very formal word. We only use it in rather legalistic contexts: [notice in a lift] Any person or persons found in possession of illegal substances will be prosecuted.
The English term, person, is ambiguous. We often use it as a synonym for human being.. But surely that is not what we intend here. It is possible that there are aliens living on other planets that have the same cognitive abilities that we do (e.g. E.T: The Extraterrestrial or the famous bar scene from Star Wars).