In 2003, of the nearly 105 million native wage and salary workers in the United States, approximately 15.4 million were affiliated with a union. Use the normal approximation to the binomial distribution to find the probability that in a national survey of 2500 workers, at most 400 will be union members.

a. Solve using normal approximation and Table 3 in Appendix B.

b. Solve using a computer or calculator and the normal approximation method.