A rapid test for presence in the blood of antibodies to HIV, the virus that causes AIDS, gives a positive result with probability about 0.004 when a person who is free of HIV antibodies is tested. A clinic tests 1000 people who are all free of HIV antibodies.
You cannot safely use the Normal approximation for this distribution. Explain why.
A. Because the Normal distribution can never be used instead of a binomial distribution.
B. Because np = 4 here, and it is too small.
C. Because np = 4 here, and it is more than 1.
D. Because np and n(1 ? p) differ from each other too much.