A real estate agent has 4 homes for sale: A, B, C, and D. Here are the listing prices. Home A: $150,000 Home B: $250,000 Home C: $190,000 Home D: $550,000 The agent wants to randomly select 2 of the 4 homes to show in an open house this coming weekend. This means the agent may show home A and B, A and C, A and D, B and C, B and D, or C and D. If homes A and B are selected, what is the sample mean listing price for this particular selection?