library_add_check Quiz: School Life

Dan Ariely decided to check the honesty of students at dormitories at MIT [1]. Here, students living in the dormitories sometimes have communal fridges. He snuck a six-pack of Coke into each communal fridge, and noted down how long it took for these to disappear. Within 72 hours, they were all gone.

For the most interesting part of the experiment, he snuck a six-pack of Coke and a plate of dollar bills into each communal fridge. After another 72 hours, all the Cokes were gone.

At the same time, how many dollar bills were gone?