[Related to the Economics in Practice on p. 28] An analysis of a large-scale survey of consumer food purchases by Mark Aguiar and Erik Hurst indicates that retired people spend less for the same market basket of food than working people do. Use the concept of opportunity cost to explain this fact.

*11. Dr. Falk is a dentist who performs two basic procedures: filling cavities and whitening teeth. Falk charges $50 per cavity filled, a process that takes him 15 minutes per tooth and requires no help or materials. For tooth whitening, a process requiring 30 minutes, Falk charges $150 net of materials. Again, no help is required. Is anything puzzling about Falk’s pricing pattern?

Explain your answer.