How can I calculate CPU utilization percent for each pluggable database running on my instance ?

Would it be correct to get elapsed time between snapshots, convert it into seconds, and multiply by cpu_count, which gives me CPU available seconds?

Then get VALUE from DBA_HIST_CON_SYS_TIME_MODEL where STAT_NAME = 'DB CPU'

And calculate the percent CPU utilized out of CPU available seconds.

e.g.

select 

(EXTRACT(day from to_timestamp(to_char(END_INTERVAL_TIME,'dd/mm/yyyy hh24:mi:ss'),'dd/mm/yyyy hh24:mi:ss') - to_timestamp(to_char(BEGIN_INTERVAL_TIME,'dd/mm/yyyy hh24:mi:ss'),'dd/mm/yyyy hh24:mi:ss'))*24*60*60 + 

EXTRACT(hour from to_timestamp(to_char(END_INTERVAL_TIME,'dd/mm/yyyy hh24:mi:ss'),'dd/mm/yyyy hh24:mi:ss') - to_timestamp(to_char(BEGIN_INTERVAL_TIME,'dd/mm/yyyy hh24:mi:ss'),'dd/mm/yyyy hh24:mi:ss'))*60*60 +