Ratio is just a single number. 4:3 can be expressed as 1.3333~ and it just says how much bigger one number is compared to another.

RE: Yes, I was able to read and understand the article. I also have 8 years of EE. Ratio is still a single number in the end. You can have an actual size of a monitor 1600 x 1200 and the ratio of sides is 1600/1200, which is just a single number. You can express it in multiple ways. You still need at least one size + understanding of what the aspect ratio is used to describe in a particular situation (units (mm, px, ...), ...) to be able to calculate the complete dimensions of a monitor screen.

Same issue with % or ppm, or whatever.

You always need a defintition to understand what the numbers are abstracting in any particular situation.