NEW YORK The latest government study on teen vaping suggests there's been little progress in keeping e-cigarettes out of the hands of kids.

The data seems to show more high school students vaping, with 14.1% saying they had done so recently, according to survey results released Thursday. In last year's survey, about 11% said they had vaped recently.

The study results were reported in Morbidity and Mortality Weekly Report, and for the 2022 survey, a 95% confidence interval of 12.4% to 16.0% was reported for the percentage of high school students saying they had vaped recently.

1. What is the interpretation of the 95% confidence interval for the percentage of high school students saying they had vaped recently?

2. Do you agree with the news headline that little progress has been made against U.S. teen vaping? Use the 95% confidence interval to justify your answer.

A randomized controlled trial performed in 2014 compared the effect of 3-month consumption of a medium-roasted coffee blend versus a dark-roasted coffee blend on body weight and cardiometabolic risk factors, including triglycerides, in overweight subjects. Triglycerides are a type of fat (lipid) found in your blood. The table below reports the triglyceride levels (mg/dl) after the coffee intervention in the two treatment groups.

Group	Number of subjects	Triglycerides (mg/dl) Mean (SD)
Medium-roasted coffee	58	124 (65)
Dark-roasted coffee	56	135 (63)

3. Compute a 95% confidence interval for the average triglyceride level for each treatment group. Report the measurement units for your confidence intervals. Show your work.

4. Is there evidence that the effects of medium-roasted coffee and dark-roasted coffee on triglyceride levels were similar or different? Use the 95% confidence intervals you computed in question 7 to justify your answer.