Final answer:
The given information does not provide the mean price of existing single-family homes three years ago.
Step-by-step explanation:
The question asks for the mean price of an existing single-family home three years ago. Since the given information only provides the median sales price for new homes, we cannot directly determine the mean price for existing homes. The median sales price for a new one-family home was $122,900 in 1990, $248,000 in 2007, $232,000 in 2008, and $294,000 in 2015, according to the U.S. Census. However, these figures only represent the prices of new homes.
To find the mean price of existing single-family homes three years ago, we would need a different data set specifically for existing homes. Without that information, it is not possible to provide an accurate answer to the question.