Suppose that there are two candidates (Jones and Johns) in the upcoming presidential election. Sara notes that she has discussed the presidential election candidates with 40 friends, and 27 said that they are voting for candidate Jones. Sara is therefore convinced that candidate Jones will win the election because Jones gets more than 50 % of votes. Answer the following questions:

a.Based on what you know about statistical inference, is Sara’s conclusion a logical conclusion? Why or why not. What inference test should she use?
b.What z-score did she obtain?
c.What should her conclusion state?
d.Compute the 95% confidence interval?
e.What role does the margin of error play in determining how many individuals should be sampled if we desired a margin of error plus or minus .000001?
f.How would you explain your conclusion to Sara without using any statistical Jargon? In other words, is her original sample size sufficient or should she interview more people to obtain an accurate prediction?

Sample Solution