i magine that a survey was conducted in Florida on the day before the November 2
ID: 3205849 • Letter: I
Question
i magine that a survey was conducted in Florida on the day before the November 2008 election. Pollsters surveyed a random sample of 60o likely voters and found that 321 of them planned to vote for Obama A Are the criteria for approximate normality of the sampling distribution satisfied? B What was the sample proportion? Give your answer as a decimal. c What is the estimated standard error for the sampling distributson of sample proportions? D what is the margin of error for a 95% confidence interval? E Give the lower and upper limits of the 95% confidence interval for the population proportion (p) of voters who planned to vote for Obama based on the sample. F Give an interpretation of this interval in the context of the problem. statway Version 3.0, o 2016 The Carnegie Foundation for the Advancement of Teaching 7.2.1 12 41Explanation / Answer
A. here n is large enough and proportion is there so we will use normal distribution.
B. sample proportion p=321/600=0.535
c. standard error=sqrt(p(1p)/n)=0.02
d. margin of error=z*standard error=1.96*0.02=0.0399
e. CI=p+/-margin of error=(0.495,0.575)
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