A study found that, in 2005, 12.5% of U.S. workers belonged to unions (The Wall Street Journal, January 21, 2006). Suppose a sample of 400 U.S. workers is collected in 2006 to determine whether union efforts to organize have increased union membership.

a. Formulate the hypotheses that can be used to determine whether union membership increased in 2006.

b. If the sample results show that 52 of the workers belonged to unions, what is the p-value for your hypothesis test?

c. At α = .05, what is your conclusion?