Historically (from about 2001 to 2005), about 58% of Americans believed that Earth’s temperature was rising (“global warming”). A March 2010 Gallup Poll sought to determine whether this proportion had changed. The poll interviewed 1014 adult Americans, and 527 said they believed that global warming was real. (Assume these 1014 adults represented a simple random sample.)

a. What percentage in the sample believed global warming was real in 2010? Is this more or less than the historical 58%?

b. Test the hypothesis that the proportion of Americans who believe global warming is real has changed. Use a significance level of 0.05.

c. Choose the correct interpretation:

i. In 2010, the percentage of Americans who believe global warming is real is not significantly different from 58%.

ii. In 2010, the percentage of Americans who believe global warming is real has changed from the historical level of 58%.