How long the duration of minor and major?

The duration of a musical minor or major scale isn't a fixed length of time. "Minor" and "major" describe the *intervals* between the notes of a scale, not its temporal duration. A piece of music written in a minor key could be 30 seconds long, or 30 minutes long – the key signature (minor or major) only dictates the *harmonic* characteristics of the music, not its length.