"Ginny sells bottled water from a small stand by the beach. On the last day of summer vacation, many people are on the beach, and Ginny realizes that she can make a lot more money this day if she hires someone to walk up and down the beach selling water. She finds a college student named Eric and makes him the following offer: They'll each sell water all day and split their earnings (revenue minus the cost of water) equally at the end of the day. Ginny knows that if they both work hard, Eric will earn $90 on the beach and Ginny will earn $180 at her stand, so they will each take home half of their total revenue: $90+$1802=$135 . If Eric shirks, he'll generate only $50 in earnings. Ginny does not know that Eric estimates his personal cost (or disutility) of working hard as opposed to shirking at $25."

Explanation:

Once out of Ginny sight, Alex faces a dilemma: Work very hard (put in all effort) or shirk (put in little effort). If he works hard, he'll sell enough water to generate $90 in earnings (not including his personal cost). If he shirks, he'll only generate $50 in earnings. After the end of the work, he'll split his earnings with Ginny and also get half of what she earns at her stand. In terms of Eric's total utility, it is worse for him to work hard. Close A If Alex works hard, Alex and Sunita together earn $270 ($180 + $90), of which Eric keeps $120. However, he loses $20 worth of utility by working hard. Therefore his net earnings is $100. If he shirks, Eric and Ginny together earn $270 ($200+ $70), of which Eric will keeps $120, while his personal cost is zero. Therefore Alex, individually, is better off when he shirks. A more better way of finding the solution to the problem is to note that from Eric's view, the amount of money he gets from Ginny's sales from the stand does not rely on his own sales.