Low memory Samsung GT-i8552


I have Samsung Galaxy GT-i8552, I was facing low memory problem in this so I erased my phone memory and factory reset my phone, after that when I checked my RAM status it was

Ram Used : 1.2 GB

Free RAM : 400 MB

Currently android 4.1.2 is installed on this phone.

I would like to know How much RAM does this mobile has ? I read on some site they stated that this phone has 1 GB of RAM whereas my mobile showing total of 1.6 GB.

Also is ther anything I can do to increase RAM on this mobile ?

I also read to root your mobile to increase storage, does anyone tried it ?