a. Determine a 98% confidence interval for the difference, p ₁ – p ₂ between the proportions of Maricopa County residents who thought that the state’s economy would improve over the next 2 years during the time of the first pool and during the time of the second poll.

b. Interpret your answer from part (a).

(Reference Problem 14)

Views on the Economy. State and local governments often poll their constituents about their views on the economy. In two polls taken approximately 1 year apart, O’Neil Associates asked 600 Maricopa County, Arizona, residents whether they thought the state’s economy would improve over the next 2 years. In the first poll, 48% said, “yes”; in the second poll, 60% said “yes”. At the 1% significance level, do the data provide sufficient evidence to conclude that the percentage of Maricopa County residents who thought the estate’s economy would improve over the next 2 years was less during the time of the first poll than during the time of the second?