Constructing and Interpreting Confidence Intervals. In Exercises use the given sample data and confidence level. In each case, (a) find the best point estimate of the population proportion p; (b) identify the value of the margin of error E; (c) construct the confidence interval; (d) write a statement that correctly interprets the confidence interval.
From an Angus Reid Public Opinion poll in which respondents were asked if they felt that U.S. nuclear weapons made them feel safer: n = 1005, x = 543 who said “yes.” Use a confidence level of 80%.
- The point estimate of the population proportion is =0.540.
- The required value is E = 0.020.
- The 80% confidence interval for the population proportion p is 0.520<p<0.560
- From the above confidence interval we can say that, we are 80% confident that the estimated population proportion will be lie between 0.520 and 0.560.