Minutes after the U.S. presidential debate of October 3, 2000, CBS News released 
the results of a poll asking a group of registered voters, "Who do you think won 
the debate?"  The results: 49% said Al Gore, 34% said George Bush, and 17% were 
undecided.  The poll reported amargin of error of +/- 5%.

  (a) Assuming Poisson statistics, about how many people were polled?
  (b) Describe at least four possible systematic errors that may have
        affected these poll results.