Issue in ubuntu server installtion version 15.10

Hi all,



       Facing some problem in ubuntu .Installed O/s but now i could not
install additional packages , GUI, etc...
When i try to install rpm using the following command it says the following
error.

   sudo apt-get install rpm

reading package lists... done + building dependency tree + reading state
information... *done e* package rpm is not available, but is referred to by
another *package* this may mean that the package is missing, has been
obsoleted, or is only available from another source + E: Package 'rpm' has
no installation candidate
<https://www.google.co.in/search?biw=1366&bih=673&q=reading+package+lists...+done+%2B+building+dependency+tree+%2B+reading+state+information...+done+e+package+rpm+is+not+available,+but+is+referred+to+by+another+package+this+may+mean+that+the+package+is+missing,+has+been+obsoleted,+or+is+only+available+from+another+source+%2B+E:+Package+'rpm'+has+no+installation+candidate&spell=1&sa=X&ved=0ahUKEwjGvfblpLjJAhUF2BoKHb8cDhgQvwUIGCgA>


My downloaded ubuntu iso file size is 550MB only.Kindly suggest me


thanks ,
Sundar
_______________________________________________
ILUGC Mailing List:
http://www.ae.iitm.ac.in/mailman/listinfo/ilugc
ILUGC Mailing List Guidelines:
http://ilugc.in/mailinglist-guidelines