POSNER, Circuit Judge.

Mrs. McCarty, 58 years old and a merchandise manager for Sears Roebuck, checked into HotelX, a large suburban resort hotel on 160 acres in St. Charles, Illinois outside Chicago, to attend a Sears business meeting. In one wall of her second-floor room was a sliding glass door equipped with a lock and a safety chain. The door opens onto a walkway that has stairs leading to a lighted courtyard to which there is public access. The drapes were drawn and the door covered by them. Mrs. McCarty left the room for dinner and a meeting. When she returned, she undressed and got ready for bed. As she was coming out of the bathroom, she was attacked by a man with a stocking mask. He beat and threatened to rape her. She fought him off, and he fled. He has never been caught. Although Mrs. McCartys physical injuries were not serious, she claims that the incident caused prolonged emotional distress which, among other things, led her to take early retirement from Sears. Investigation of the incident by the police revealed that the sliding glass door had been closed but not locked, that it had been pried open from the outside, and that the security chain had been broken. The intruder must have entered Mrs. McCartys room by opening the door to the extent permitted by the chain, breaking the chain, and sliding the door open the rest of the way. Then he concealed himself somewhere in the room until she returned and entered the bathroom. Mrs. McCartys theories of negligence are that the defendant should have made sure the door was locked when she was first shown to her room; should have warned her to keep the sliding glass door locked; should have equipped the door with a better lock; should have had more security guards (only two were on duty, and the hotel has more than 500 rooms); should have made the walkway on which the door opened inaccessible from ground level; or should have done some combination of these things. There are various ways in which courts formulate the negligence standard. The analytically (not necessarily the operationally) most precise is that it involves determining whether the burden of precaution is less than the magnitude of the accident, if it occurs, multiplied by the probability of occurrence. (The product of this multiplication . . . is what economists call an expected accident cost.) If the burden is less, the precaution should be taken. This is the famous Hand Formula announced in United States v. Carroll Towing

QUESTIONS: 1. Who should win this negligence action (Plaintiff Ms. McCarty or Defendant HotelX)?

2. With respect to your answer to #1 above, why?

3. What reasonable legal arguments support the other Party?