In one of his books, Ted Sorenson, Special Counsel to President John F. Kennedy, presents an intimate biography of the extraordinary man. According to Sorenson, Kennedy “read every fiftieth letter of the thirty thousand comings weekly to the White House.” What type of sampling design was Kennedy using in this case? Explain your answer. [SOURCE: From Kennedy: The Classical Biography by Ted Sorenson. Published by Harper Perennial, 2009.]