As you said, Sprite is owned by Coca-Cola, so you need to look for Coca-Cola in the listings. In trading, they use what is called the NASDAQ National Market System. In this system, each company has a symbol. By looking for this symbol in the stocks, you can find out the closing price in the newspaper or on the Internet.
There are several different divisions of Coca-Cola represented. Here are the names of the corporations and their symbols:
Coca-Cola Bottling Co Consolidated - COKE Coca-Cola Co (Coke) - KO Coca-Cola Enterprises Inc - CCE Coca-Cola Femsa SA de CV - KOF
Closing prices will change at the close of each trading day. Yahoo is a good place to get these quotes. Just go to this link:
Also, if you know the company you are looking for and don't know they symbol, you can do a Symbol Lookup. You can then type in the name of the company or just look it up in their alphabetical listing. I used the listing to come up with Coke's symbols.
That's a cool questions and I think I've learned something here, too. Good luck on your project.