Here are some books to help reporters work better with numbers:
Cohn, Victor. News & Numbers. 1989. Iowa State University Press.
Crossen, Cynthia. Tainted Truth: The Manipulation of Fact in America. 1994. Simon & Schuster.
Meyer, Philip. The New Precision Journalism. 1991. Indiana University Press.
The Economist Numbers Guide: The Essentials of Business Numeracy. 1993. Penguin Books.
Paulos, John Allen. Innumeracy: Mathematical Illiteracy And Its Consequences. 1988. Hill and Wang.