DELL Inspiron 3542

I recently bought Dell Inspiron 3542 with Ubuntu 12.04 LTS preinstalled on it.

For some reason I had to restore my system back to the 'out of box' state.
So, using Dell Recovery Tool I performed system restore. Everything went fine and I had my system back to the 'out of box' state.

But I noticed afterwards that last partition(containing both Extended and Linux-swap space) on the disk has increased from 8GB(previously) to 17GB and I have no idea why? 

Below is the current partition table(after system restore) :-

Model: ATA ST1000LM024 HN-M (scsi)
Disk /dev/sda: 1000GB
Sector size (logical/physical): 512B/4096B
Partition Table: msdos

Number  Start   End     Size           Type          File system     Flags
 1      1049kB  368MB   367MB      primary     fat32               diag
 2      368MB   3589MB  3221MB   primary    fat32                lba
 3      3589MB  983GB   980GB      primary    ext4                 boot
 4      983GB   1000GB  17.0GB     extended
 5      983GB   1000GB  17.0GB     logical      linux-swap(v1

Before system restore,

1. 'Number 3' used to END at 992 GB and' Number 4' & 'Number 5' used to START at 992GB.

2. Size of 'Number 4' and 'Number 5' was 8387MB.

3. Everything else was same as it is seen in above table.

I want to bring disk partitions back to previous state and also want to know the reason that why this thing happened?

Please help!!!