premise: Arnold Rampersad (born 13 November 1941) is a biographer and literary critic, who was born in Trinidad and Tobago and moved to the US in 1965. The first volume (1986) of his "Life of Langston Hughes" was a finalist for the Pulitzer Prize and his "Ralph Ellison: A Biography" was a finalist for the 2007 National Book Award.
hypothesis: Arnold Rampersad was in his sixties when "Ralph Ellison: A Biography" was a finalist in the National Book Award.
reason: He was born in 1941 and the competition was in 2007 - he would be in his sixties.