Hypotheses Write the null and alternative hypotheses you would use to test each of the following situations:

a) A president is concerned about his “positives”—the percentage of the country’s residents who express approval of his job performance. His political committee pays for a series of TV ads, hoping that they can keep the positives above 65%. They will use follow-up polling to assess the ads’ effectiveness.

b) In the 1980s only about 13% of the population attained a bachelor’s degree. Has the percentage changed?

c) Only about 27% of people who try to earn money succeed. Sellers of a motivational tape claim that listening to the recorded messages can help people succeed.