As part of a quality control program for a catalyst manufacturing line, the raw materials (alumina and a binder) are tested for purity. The process requires that the purity of the alumina be greater than 85%. A random sample from a recent shipment of alumina yielded the following results (in percent): 93, 87, 92, 90.
Select the appropriate null and alternate hypothesis:
Ha: μ < 85
H0: μ ≥ 85