Oracle 11g – How to login "scott/tiger" accounts after installment

After I have successfully installed the Oracle 11g, I wanted to use SQL*plus. However, when I tried to connect database as  login name: sys, I found the account is locked.  Later I tried to login with "system" account, then alter and active scott/tiger. Here are steps for these actions.

1. SQL> conn user/password;

SQL> conn sys/private password;

Error message is displayed: the account is locked.

2. Try to login as "system"   - pass

SQL> conn  system/password;

3. Unlock "scott"

SQL> alter user scott account unlock;

4. Can change "tiger":

SQL> alter user scott identified by tiger;

5. SQL> conn scott/tiger;    -Success