Final answer:
A modern biography of George Washington is a secondary source because it is based on analyzing and synthesizing information after the fact, rather than including new, original research or documentation from the time of his life.
Step-by-step explanation:
A biography of George Washington written in modern times would be considered a secondary source because it is compiled from information that was created after the events of Washington's life have already taken place. This distinguishes it from primary sources, which are contemporary to the events they describe, such as diary entries or letters written by Washington himself. Secondary sources are valuable for providing context and analysis, drawing upon a variety of primary documents and other secondary materials to offer a broader perspective on the subject.
An example of a primary source would be a diary entry by George Washington, whereas a biography written today about his life would reflect the writer's interpretation of historical events and primary documents. Thus, the strength of a secondary source like a modern biography lies in its ability to analyze and synthesize information from various credible sources, rather than presenting new, original research.