1) Accepting a flat rate of $15 for a night's work or:
2) Choosing two amongst six envelopes, two containing $1 bills, two containing $5 bills, one wth a $10 bill, and one with a $20 bill.
Note that the second option could leave you with as little as $2(choosing $1 both times) or as much as $30 (choosing the $10 and the $20).
Assuming that you were going to babysit for a long, long time which is the better payment option?