Radon is a colorless, odorless, invisible gas that seeps into residential homes and has been linked

to lung cancer. A generally acceptable safe level of radon is 4 pCi/L. A random sample of 32 homes in

a certain county in West Virginia was obtained and the radon level in each was carefully measured.

The sample mean was f = 4.9 with a standard deviation of s = 2.1.

(a) Do these data provide convincing evidence at the 01 = 0.05 significance level that the mean radon

level in this county is too high? Use a significance level of 5%.

(b) A 95% confidence interval for 1-1 is 4.14 to 5.66 pCi/L. Explain how this interval gives results

consistent with the test in part a.