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

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.At a 5% significance level,the decision is to ________________________________________________.

A) reject H_o;we can conclude that the mean concentration of radon gas is greater than the safe level
B) reject H_o;we cannot conclude that the mean concentration of radon gas is greater than the safe level
C) not reject H_o;we can conclude that the mean concentration of radon gas is greater than the safe level
D) not reject H_o;we cannot conclude that the mean concentration of radon gas is greater than the safe level