It is a beautiful spring day so you decide to go rowing upstream on your favorite river. You row at a constant rate of 1 mile per hour. Suddenly a gust of wind blows your hat off into the water. You watch it float away downstream but since you never really liked it that much, you continue to row upstream for 10 minutes. Wait! You just remember that you had tucked your concert tickets in the hat! Quickly, you turn around and row downstream at the same rate looking for the hat. You finally catch up to it at the same place that you started out from, and rescue your tickets.
What is the speed of the current?