question 14.) In April 2015, the U.S. Department of Health and Human Services released its recommendation for an optimal concentration of fluoride at 0.7 mg per liter of water. Technicians at a local water treatment took 10 random specimens from the water supply to see if their level of fluoridation was optimal and found a 99% confidence interval for the mean fluoride concentration to be 0.68 < < 0.92 mg per liter.

Select ALL appropriate conclusions.

Select one or more:

a.The sample mean was 0.8 mg per liter and the margin of error is 0.12

b.It is not possible to determine the sample mean from the confidence interval given.

c.The fluoride level IS optimal since 0.7 is in the interval.

d.If technicians had taken a different sample of size 10, there is a 99% chance its sample mean would be between 0.68 and 0.92 mg per liter.

e.IF it was possible to take all samples of size n=10, 99% of them would produce confidence intervals that would include the true, but unknown, mean fluoride concentration, but they wouldn't necessarily be 0.68 < < 0.92.

f.The fluoride level is NOT optimal since 0.7 is in the interval.