Homework...mmm, there's always the Bird approach - "if it don't fit, drill more holes".
To be serious for a moment, I think the opinions are divided about where the fan should be - some people say on the back of the tube, and some say on the side of the tube like where you have it, or even down a bit so it's blowing/sucking partially onto the side of the mirror.
Where most people agree is that if you have a passive fan arrangement then you're better off sucking the hot air out of the tube. The computer case and power supply manufacturers worked that out many years ago.
Bird