National standards call for blood lead levels less than 10 g/dL among children. A random sample of 28 children from Skid Row Elementary School yielded a sample mean blood lead level of x = 13:3 g/dL and a corresponding sample standard deviation of s = 8:2 g/dL.

(a) Test the null hypothesis H0 : = 10 g/dL against Ha : > 10 g/dL at the = 0:05 level. Give your test statistic, degrees of freedom, and critical value. (b) Compute a 95% condence interval for the mean blood lead level of children attending Skid Row Elementary.

(c) What can you conclude from the above analyses?

(d) Let denote the mean blood lead level of children attending Skid Row Elementary, and (a, b) denote the 95% condence interval you obtained in part (b). Which of following is (are) true?

1. There is a 95% probability that is between a and b.

2. There is a 95% probability that is 13.3.

3. If we took many additional random samples of the same size and from each computed a 95% condence interval for , approximately 95% of these intervals would contain .

4. If we took many additional random samples of the same size and from each computed a 95% condence interval for , approximately 95% of the time would fall between a and b.

5. All above