How to find out expected time of completion for an oracle query

From oracle 10 g onwards we have got an option to check how long a query will run,to find out expected time of completion for a query.

 Script:This script is using v$session_longops

SELECT
opname,
target,
ROUND((sofar/totalwork),4)*100 Percentage_Complete,
start_time,
CEIL(time_remaining/60) Max_Time_Remaining_In_Min,
FLOOR(elapsed_seconds/60) Time_Spent_In_Min
FROM v$session_longops
WHERE sofar != totalwork;

Script:Should have acess to v$sqlarea table 

SELECT 
opname
target,
ROUND((sofar/totalwork),4)*100 Percentage_Complete,
start_time,
CEIL(TIME_REMAINING  /60) MAX_TIME_REMAINING_IN_MIN,
FLOOR(ELAPSED_SECONDS/60) TIME_SPENT_IN_MIN,
AR.SQL_FULLTEXT,
AR.PARSING_SCHEMA_NAME,
AR.MODULE client_tool
FROM V$SESSION_LONGOPS L, V$SQLAREA AR
WHERE L.SQL_ID = AR.SQL_ID 
AND TOTALWORK > 0
AND ar.users_executing > 0
AND sofar != totalwork;