The desired amount of a chemical component X in a certain ty

The desired amount of a chemical component (X) in a certain type of aluminous cement is 5.5. To test whether the true average amount is 5.5 for a production facility, 16 independent samples are analyzed. Suppose that the amount of component X in a sample is normally distributed with = 0.3 and that the sample mean is = 5.25. What is the absolute value of the threshold of the rejection region?

A) 2.33

B) 2.947