Open StatCrunch Select Stat Calculator Normal → → → → Between→ Input = 0.95 Compute P X (____≤ ≤ _____) → 1.96 = √ = 1.96*√= * ≈ 0.023716 The confidence interval is = 0.18 ± 0.0237 = (0.1563, 0.2037). This interval means that we are 95% confident that 15.63% to 20.37% of adult Americans dreaded Day. Valentine’s Method II --> Use StatCrunch to find the C. I. Open StatCrunch Stat Proportion Stats One Sample with summary Input number → → → → → of successes --> 180 (18% of 1000) and observations --> 1000, select confidence interval and input 95% compute and record results → Example 4: Construct a confidence interval of the population proportion at the given level of confidence. confidence = = = 0.4 Method I--> Use the C. I. formula --> Open StatCrunch Select Stat Calculator Normal Between → → → → → Input = 0.96 Compute P (___≤X ≤ _____) → 2.05. ≈ * √ = 2.05*√= * = 2.05*0.0346 = 0.071 The 96% confidence interval is = 0.40 ± 0.071 = (0.329, 0.471). Method II --> Use StatCrunch to find the C. I. Open StatCrunch Stat Proportion Stats One Sample with summary Input number → → → → → of successes --> 80 and observations --> 200, select confidence interval and input 96% → compute and record results Example 5: In a study of 1228 randomly selected medical malpractice lawsuits, it is found that 856 of them were later dropped or dismissed.
Open StatCrunch → Select Stat → Calculator → Normal → Between→ Input P (____≤ X ≤ _____) = 0.95 → Compute = 1.96 * √ = 1.96*√= ≈ 0.023716 The confidence interval is = 0.18 ± 0.0237 = (0.1563, 0.2037). This interval means that we are 95% confident that 15.63% to 20.37% of adult Americans dreaded Valentine’s Day. Method II --> Use StatCrunch to find the C. I. Open StatCrunch → Stat → Proportion Stats → One Sample → with summary → Input number of successes --> 180 (18% of 1000) and observations --> 1000, select confidence interval and input 95% → compute and record results Example 4: Construct a confidence interval of the population proportion at the given level of confidence. confidence = = = 0.4 Method I--> Use the C. I. formula --> Open StatCrunch → Select Stat → Calculator → Normal → Between → Input P (___≤X ≤ _____) = 0.96 → Compute ≈ 2.05. * * √ = 2.05*√= = 2.05*0.0346 = 0.071 The 96% confidence interval is = 0.40 ± 0.071 = (0.329, 0.471). Method II --> Use StatCrunch to find the C. I. Open StatCrunch → Stat → Proportion Stats → One Sample → with summary → Input number of successes --> 80 and observations --> 200, select confidence interval and input 96% → compute and record results Example 5: In a study of 1228 randomly selected medical malpractice lawsuits, it is found that 856 of them were later dropped or dismissed.