There is No Password

Do not try to guess the root password, that is impossible. Instead, realise the truth... there is no root password. Then you will see that it is 'sudo' that grants you access and not the root password.

sudo -V | -h | -l | -L | -v | -k | -K | -s | [ -H ] [ -P ] [ -S ] [ -b ] | [ -p prompt ] [ -c class|- ] [ -a auth_type ] [ -u username|#uid ] command

sudo allows a permitted user to execute a command as the superuser or another user, as specified in the sudoers file. The real and effective uid and gid are set to match those of the target user as specified in the passwd file (the group vector is also initialized when the target user is not root). By default, sudo requires that users authenticate themselves with a password (NOTE: by default this is the user's password, not the root password). Once a user has been authenticated, a timestamp is updated and the user may then use sudo without a password for a short period of time (5 minutes unless overridden in sudoers).