How to Authorize Password changes via sudo

Problem: you want to permit a user to change the passwords of certain other users.
 
Solution: To permit smith to change the passwords of jones, chu, anf agarwal:

/etc/sudoers:
smith ALL = NOPASSWD: /usr/bin/passwd jones, /usr/bin/passwd chu, /usr/bin/passwd agarwal 

The NOPASSWD tag is optional.