1. The problem statement, all variables and given/known data Link to problem: http://img147.imageshack.us/my.php?image=soundqj3.png 2. Relevant equations No idea, One of the reasons I'm asking. >.> 3. The attempt at a solution Ok, I have no idea how to even begin this problem. I need a hint in the right direction, or just what the formula I need here. Thanks in advance.