This lecture covers the concepts of acceptable price and probable price in the real estate market, discussing individual preferences, market value, and negotiation potential. It explains the conditions for determining the probable price, different approaches for estimation, and tricks for comparing prices of different properties. The lecture also delves into calculating a reference price using average prices and weighted averages, illustrated graphically. It concludes with a summary of the differences between acceptable and probable prices, indirect and direct estimation methods, and introduces additional estimation techniques.