When Sony was busy creating the Compact Disc or CD, they had a problem to contend with: how much data should it store? The more data they could store, the more expensive it would be and so on. In the end they chose a limit; the average CD today can hold 74 minutes worth of music.
This rather unusual length was chosen by Sony’s president at the time Norio Ohga. His reasoning behind the 74 minute limit was that a single CD should be able to contain the longest recorded version of Beethoven’s Ninth Symphony; and that it did indeed. There is a second, also common CD format that can hold 80 minutes of audio, but that is far less interesting.