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 3 points with 99% confidence assuming s = 19.4 based on earlier studies? Suppose the doctor would be content with 90% confidence. How does the decrease in confidence affect the sample size required? Click the icon to view a partial table of critical values. - X A 99% confidence level requires subjects. (Round up to the nearest subject.) Partial Critical Value Table A 90% confidence level requires subjects. (Round up to the nearest subject.) Level of Confidence, How does the decrease in confidence affect the sample size required? Area in Each Tail, Critical Value, Za /2 (1 - () . 100% 90% 0.05 1.645 A. Decreasing the confidence level decreases the sample size needed. 950 0.025 1.96 O B. Decreasing the confidence level increases the sample size needed. 9% 0.005 2.575 O C. The sample size is the same for all levels of confidence. Print Done