Available cpu in AWR report 12c

Dear experts,

Our db version 12.1.0.2

Please let us know how to calculate available or maximum cpu in awr report that is taken for 30min interval.

Example 1

WORKLOAD REPOSITORY report for DB Name         DB Id    Instance     Inst Num Release     RAC Host ------------ ----------- ------------ -------- ----------- --- ------------ xxxx         xxxxxxxxx   xxxx               1 10.2.0.4.0  NO  xxxxxxxxx               Snap Id      Snap Time      Sessions Curs/Sess             --------- ------------------- -------- --------- Begin Snap:     66607 02-Mar-12 12:00:52       648      19.6   End Snap:     66608 02-Mar-12 12:30:54       639      21.4    Elapsed:               30.04 (mins)    DB Time:            3,436.49 (mins) ... Top 5 Timed Events                                         Avg %Total ~~~~~~~~~~~~~~~~~~                                        wait   Call Event                                 Waits    Time (s)   (ms)   Time Wait Class ------------------------------ ------------ ----------- ------ ------ ---------- resmgr: cpu quantum                 475,956     152,959    321   74.2  Scheduler CPU time                                         47,879          23.2