Nissan Repair: Alternator or Battery, nissan altima, blockbuster video

Question
How do you know if it's your alternator or battery that is going bad?  My daughter has a 94 Nissan Altima.  She was driving and her radio stopped playing.  She went into the Blockbuster Video, came out and her car wouldn't start.  She got a jump from someone and her car cranked.  Is that her battery or is her alternator going bad and not keeping the battery charged?

Answer
I would need more information.  Go to Autozone and have them check the charging system.  I would assume that the alternator is on its way out.  But, I do not know when the battery was replaced last.  Since it started up and drove home with a jump the alternator has to be working.  So, if I tell you get a battery and the alternator is going bad but not all the way I would be giving you bad information.  The best way is to have the system checked and Autozone will do it for free.  Have them check it and you will know for sure.  Drope me a note and let me know how it goes.