E Test: POST UNIT 6 - TEST - Ch. 9 Question 10 of 13 This test: 13 point(s) possible This question: 1 point(s) possible A simple random sample of size n is drawn. The sample mean, x, is found to be 19.3, and the sample standard deviation, s, is found to be 4.2. Click the icon to view the table of areas under the t-distribution. (a) Construct a 95% confidence interval about u if the sample size, n, is 34. Lower bound: ; Upper bound: (Use ascending order. Round to two decimal places as needed.) (b) Construct a 95% confidence interval about u if the sample size, n, is 51. Lower bound: ; Upper bound: (Use ascending order. Round to two decimal places as needed.) How does increasing the sample size affect the margin of error, E? O A. The margin of error increases. O B. The margin of error decreases. O C. The margin of error does not change. (c) Construct a 99% confidence interval about u if the sample size, n, is 34. Lower bound: ; Upper bound: (Use ascending order. Round to two decimal places as needed.) Compare the results to those obtained in part (a). How does increasing the level of confidence affect the size of the margin of error, E? O A. The margin of error decreases. O B. The margin of error increases. O C. The margin of error does not change. (d) If the sample size is 14, what conditions must be satisfied to compute the confidence interval? O A. The sample must come from a population that is normally distributed and the sample size must be large. O B. The sample size must be large and the sample should not have any outliers. O C. The sample data must come from a population that is normally distributed with no outliers.E Test: POST UNIT 6 - TEST - Ch. 9 Question 13 of 13 This test: 13 point(s) possible This question: 1 point(s) possible Submit test 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 2 points with 99% confidence assuming s = 17.6 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. A 99% confidence level requires subjects. (Round up to the nearest subject.) A 90% confidence level requires | | subjects. (Round up to the nearest subject.) X How does the decrease in confidence affect the sample size required? Partial Critical Value Table O A. Decreasing the confidence level decreases the sample size needed. Level of Confidence, O B. Decreasing the confidence level increases the sample size needed. Critical Value, Zo/2 (1 - () . 100% Area in Each Tail, 7 O C. The sample size is the same for all levels of confidence. 90% 0.05 1.645 95% 0.025 1.96 99% 0.005 2.575 Print Done