Relative size of sga_max_size and sga_target to the physical memory

Dear Experts,
I have installed oracle 10.2.0.4 on AIX 5.3 with 32 GB of physical memory.
Let us say other applications on the server consume 10 GB of physical memory.
Now how should i plan the size of SGA_TARGET and SGA_MAX_SIZE on the same.

As per Oracle® Database Performance Tuning Guide 10g Release 2 (10.2):
You must then divide the resulting memory between the SGA and the PGA.
For OLTP systems, the PGA memory typically accounts for a small fraction of the total memory available (for example, 20%), leaving 80% for the SGA.
For DSS systems running large, memory-intensive queries, PGA memory can typically use up to 70% of that total (up to 2.2 GB in this example).
Good initial values for the parameter PGA_AGGREGATE_TARGET might be:
For OLTP: PGA_AGGREGATE_TARGET = (total_mem * 80%) * 20%
For DSS: PGA_AGGREGATE_TARGET = (total_mem * 80%) * 50%
where total_mem is the total amount of physical memory available on the system.
(http://download-west.oracle.com/docs/cd/B19306_01/server.102/b14211/memory.htm#i49320)

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