Step 1: You take a test. Step 2: They decide if you'll return the $1000. If they think you will, they put $1 000 000 in the case. If they think you won't, or they think you'll pull some shenanigans, they put blank paper in the case. Step 3: The attendant walks in with the case, hands it to you, and leaves with whatever envelope you give him.
Thus, you get whatever was in the case plus whatever was in the envelope you kept. Simple as that.
(As for the prediction step, I don't know how they do it - all I know is that they've been right one hundred times out of a hundred.)
Sorry, sorry! I'll be more careful next time!
Step 2: They decide if you'll return the $1000. If they think you will, they put $1 000 000 in the case. If they think you won't, or they think you'll pull some shenanigans, they put blank paper in the case.
Step 3: The attendant walks in with the case, hands it to you, and leaves with whatever envelope you give him.
Thus, you get whatever was in the case plus whatever was in the envelope you kept. Simple as that.
(As for the prediction step, I don't know how they do it - all I know is that they've been right one hundred times out of a hundred.)