quicktime has no sound?

I am taking some online college classes, and my instructor had us download quicktime. I did this, and got onto the quiz that was to check to make sure quicktime was working. I clicked the play button, to play the audio, but no sound came out. I had seen it completely load. The bar moved along as if it was playing. My volume is all the way up on my computer and on the player. I have tried this in google chrome, firefix, internet explorer, and in safari. How do you get ot to play sound. I have also uninstalled and reinstalled it.