Radon is a colorless and odorless radioactive gas that can accumulate in residential homes. High levels of exposure can lead to health problems. Radon levels are measured in units of picocuries per liter (pCi/L).The recommended radon level is less than 4 pCi/L.A housing development has 101residential homes.The homeowners association would like to estimate the average radon level in the development. Because it would be too expensive to measure everyhome, a random sample of 30 homes was selected to betested, and the average radon level was found to be 1.3 pCi/L.Assume from past studies the population standard deviation of radon levels in homes is 0.5pCi/L.

a.) The 90% confidence interval to estimate the average radon level is (_____ pCi/L,_____pCi/L).

(Round to two decimal places as needed.)