July is National Grilling Month in the United States. On July 1, 2008, The Harris Poll #70 reported on a survey of Americans’ grilling preferences. When asked about their favorite food prepared on a barbeque grill, 662 of 1,250 randomly sampled Democrats preferred steak, as compared to 586 of 930 randomly sampled Republicans.
a. Give a point estimate for the proportion of all Democrats who prefer steak as their favorite barbeque food.
b. Give a point estimate for the proportion of all Republicans who prefer steak as their favorite barbeque food.
c. Give a point estimate for the difference between the proportions of all Democrats and all Republicans who prefer steak as their favorite barbeque food.
d. Construct a 95% confidence interval for the difference between the proportions of all Democrats and all Republicans who prefer steak as their favorite barbeque food.
e. Give a practical interpretation of the interval, part d.
f. Explain the meaning of the phrase “95% confident” in your answer to part e.