Guyon sorry not a noob question - it was my mistake
The aspect ratio I provided is 3:2 (safe zone = 960 X 640)
3:2 is a good/perfect choice - especially for Apple products
Iphone 4 640*960
Iphone 5 640*1136
It all depends on your kind of game. So for static games like puzzle or dressup - scale outer should be considered.