Question

Periodically, a town water department tests the the drinking water of homeowners for contaminants such as lead. The lead levels in water specimens collected for a sample of 10 residents of the town had a mean of 2.8 ​mg/L and a standard deviation of 2.7 ​mg/L. Complete parts a through c.

a. Construct a 90​% confidence interval for the mean lead level in water specimens from the town.

b. Interpret the interval in terms of this application. Choose the correct answer below.

A. The water department can be 10​% confident that the mean lead level in drinking water for all residents in the town is within this interval.

B. The water department can be 90​% confident that the mean lead level in drinking water for all residents in the town is 2.8mg/L.

C. The water department can be 90​% confident that the mean lead level in drinking water for all residents in the town is within this interval.

D. The water department can be 90​% confident that the mean lead level in drinking water for all residents in the town is outside this interval.

E. The water department is confident that 90​% of the mean lead level in drinking water for all residents in the town is described by this interval.

c.The phrase "90​% confidence​ interval" means that if many intervals were constructed using the same methods and the same ____________________ then____% of those intervals would contain the true _________________.

Answer 1