A doctor wants to estimate the mean HDL cholesterol of all20- to29-year-old females. How many subjects are needed to estimate the mean HDL cholesterol within 3 points with 99% confidence assuming s=13.3 based on earlierstudies? Suppose the doctor would be content with 95% confidence. How does the decrease in confidence affect the sample sizerequired?

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A99% confidence level requires ____subjects. (Round up to the nearestsubject.)

A 95% confidence level requires ______subjects. (Round up to the nearestsubject.)

How does the decrease in confidence affect the sample sizerequired?

A.

Decreasing the confidence level decreases the sample size needed.

B.

The sample size is the same for all levels of confidence.

C.

Decreasing the confidence level increases the sample size needed.

2.One year Mike had the lowest ERA(earned-run average, mean number of runs yielded per nine inningspitched) of any male pitcher at hisschool, with an ERA of 2.86. Also, Kate had the lowest ERA of any female pitcher at the school with an ERA of 2.68. For themales, the mean ERA was 4.088 and the standard deviation was 0.751. For thefemales, the mean ERA was 4.899 and the standard deviation was 0.667. Find their respectivez-scores. Which player had the better year relative to theirpeers, Mike or Kate? (Note: Ingeneral, the lower theERA, the better thepitcher.)

Mike had an ERA with az-score of ______

Kate had an ERA with az-score of _____(Round to two decimal places asneeded.)

Which player had a better year in comparison with theirpeers?

A.

Kate had a better year because of a lowerz-score.

B.

Mike had a better year because of a higherz-score.

C.

Mike had a better year because of a lowerz-score.

D.

Kate had a better year because of a higherz-score.

3.A random sample of 40 adults with no children under the age of 18 years results in a mean daily leisure time of 5.69 hours, with a standard deviation of 2.32 hours. A random sample of 40 adults with children under the age of 18 results in a mean daily leisure time of 4.34 hours, with a standard deviation of 1.96 hours. Construct and interpret a 95% confidence interval for the mean difference in leisure time between adults with no children and adults with children 12.

Let 1 represent the mean leisure hours of adults with no children under the age of 18 and 2 represent the mean leisure hours of adults with children under the age of 18.

The 95% confidence interval for 12 is the range from____hours to ___hours.

(Round to two decimal places asneeded.)

What is the interpretation of this confidenceinterval?

A.

There is 95% confidence that the difference of the means is in the interval. Conclude that there is a significant difference in the number of leisure hours.

B.

There is 95% confidence that the difference of the means is in the interval. Conclude that there is insufficientevidenceofa significant difference in the number of leisure hours.

C.

There is a 95% probability that the difference of the means is in the interval. Conclude that there is insufficient evidence of a significant difference in the number of leisure hours.

D.

There is a 95% probability that the difference of the means is in the interval. Conclude that there is a significant difference in the number of leisure hours.