In this instance, I think I could justify an improper fraction.
We all know what a 16:9 screen is. An 18:9 screen is obviously wider.
It's not IMMEDIATELY obvious that a 2:1 screen is wider than a 16:9 screen for the layman, however.
People don't handle ratios well. I've had any number of arguments over this, and also that it's measured by screen diagonal.
No, a 65" 4:3 smartboard is NOT the same as a 65" 16:9 touchscreen. In fact, you lose quite a bit of height and it looks tiny and stupid in comparison.