The EPA sets an airborne limit of 5 parts per million(ppm) on vinylchloride, a colorless gas used to makeplastics, adhesives, and other chemicals. It is both a carcinogen and a mutagen(New Jersey Department ofHealth, Hazardous Substance FactSheet, 2005). A major plasticsmanufacturer, attempting to control the amount of vinyl chloride its workers are exposedto, has given instructions to halt production if the mean amount of vinyl chloride in the air exceeds 3.0 ppm. A random sample of 50 air specimens is taken. The mean is found to be 3.7 ppmwithastandarddeviationof0.09ppm.Which of the following statements iscorrect?

A.This is a ttest on the mean of a population.

B.This is a ztest on the proportion of a population.

C.This is a ttest on the proportion of a population.

D.This is a ztest on the mean of a population.

E.None of the above