The ave 3min/song estimate is probably a little low. Radio edits are around that length but the original tracks tend to be longer. (Seen another way; most CD

The ave 3min/song estimate is probably a little low. Radio edits are around that length but the original tracks tend to be longer. (Seen another way; most CDs are longer than 30min but tend to have 10 tracks, since many of the contracts will effectively not pay royalty on tracks > 10)