I just found the TCPI formula on following page is incorrect.

http://pmzilla.com/formulas-pmp-pmp

12. To Complete Performance Index TCPI
 Values for the TCPI index of less then 1.0 is good because it indicates the efficiency to complete is less than planned. How efficient must the project team be to complete the remaining work with the remaining money?

( BAC - EV ) / ( BAC - AC )