Samantha and Rashida are planning a trip to Padre Island, Texas, during spring break. Members of the varsity volleyball team, they are looking forward to four days of beach volleyball and parasailing. They will drive Samantha’s car and estimate that they will pay the following costs during the trip:
Motel (4 nights at $145) ........$580
Food (each) ............. 150
Gas in total ............ 120
Parasailing and equipment rental (each) ... 125
They have reservations at the SeaScape Motel, which charges $120 per night for a single, $145 per night for a double, and an additional $15 per night if a rollaway bed is added to a double room. Samantha’s little sister, Kallie, wants to go along. She isn’t into sports but thinks that four days of partying and relaxing on the beach would be a great way to unwind from the rigors of school. She figures that she could ride with Samantha and Rashida and share their room.

Required:
1. Using incremental costs only, what would it cost Kallie to accompany Samantha and Rashida?
2. Using the benefits-received method, what would it cost Kallie to go on the trip?