Want Whole Row To Shade Gray When Drop Down Item In Row = "completed"

I have a a worksheet with a drop down menu in one column to show various completion status options (Not started, In progress and Completed). I was able to use conditional formatting to change the color of the cell to gray when I choose "completed" from the drop down menu, but I would like the whole row in view (about 8 cells across) to shade to gray when I choose "completed" from the drop down - not just the completed cell. I'm thinking an IF statement would work, but I don't know how to use an IF statement to shade a range of cells a color.