Question

We survey 1,600 people on their opinions about state tax policy in a given state. 20% of the survey participants support an increase in property tax.We want to examine the population proportion of public opinions using this sample proportion.

a. Calculate the 95% confidence interval for the survey participants supporting an increase in property tax AND interpret the interval

b. In a follow up survey, which we are able to find 625 people (survey participants in the second survey is a subset of those in the first survey). 25% of the survey participants, in this second-wave survey, support an increase in property tax. We set up a null hypothesis that the proportions in two surveys (20% v.s. 25%) are not different, and an alternative hypothesis that the proportions are different. using α=0.05, test whether the two proportions are significantly different.

Answer 1