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.
Persons is a word and it is listed in many dictionaries as the plural of person along with people. I find that persons is used when the writer is trying to sound politcally correct, or in a sort of social studies context. E.G. persons with disabilities or indigenous persons. In most cases, you should use people.