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 following link gives you a good idea of the traditional usage of the word people as opposed to persons: http://www.bartleby.com/61/64/P0176400.html. In very formal contexts, persons is preferable to people in situations like the examples given, but anytime else, it just seems pretentious.