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Determine the point estimate of the population mean and margin of error for the confidence interval. Lower bound is 23, upper bound is 27. The point estimate of the population mean is.A doctor wants to estimate the mean HDL cholesterol of all 20- to 29-year-old females. How many subjects are needed to estimate the mean HDL cholesterol within 4 points with 99% confidence assuming s = 11.3 based on earlier studies? Suppose the doctor would be content with 95% confidence. How does the decrease in confidence affect the sample size required? Click the icon to view a partial table of critical values. A 99% confidence level requires subjects. (Round up to the nearest subject.) X Partial Critical Value Table Level of Confidence, Critical Value, Za /2 (1 -a) . 100% Area in Each Tail, - 90% 0.05 1.645 95% 0.025 1.96 99% 0.005 2.575 Print Done