A Schoolteacher Is Worried That the Concentration of Dangerous, Cancer-Causing

Multiple Choice

A schoolteacher is worried that the concentration of dangerous, cancer-causing radon gas in her classroom is greater than the safe level of 4pCi/L. The school samples the air for 36 days and finds an average concentration of 4.4pCi/L with a standard deviation of 1pCi/L. The value of the test statistic is ________.

A) t₃₅ = -2.40
B) z = -2.40
C) t₃₅ = 2.40
D) z = 2.40