What is the Survey Contest?
First things first; in order to participate in this weekly Survey Contest, you have to join MetaRL first. By registering, you get access to Surveys and other offerings that gives out metaPoints (you can convert metaPoints to Linden Dollars).
So what is the Survey Contest? Basically it gives bonus metapoints to the one who completes the most number of Survey in a week.
To quote MetaRL:
The Surveys contest is a weekly contest and the winner is decided based on who completes the most surveys in a single week.
Duration: Weekly - Ends on Tuesday at 4pm EST
1st Place: 2,500 metaPoints
2nd Place: 1,500 metaPoints
3rd Place: 500 metaPoints
Now that's more free linden dollars for you every week!