Acopper smelting process is supposed to reduce the arsenic content of the copper to less than 1000 ppm. let μ denote the mean arsenic content for copper treated by this process, and assume that the standard deviation of arsenic content is σ=100 ppm. the sample mean arsenic content xˉ of 75 copper specimens will be computed, and the null hypothesis h0: μ≥1000 will be tested against the alternate h1: μ< 1000. a. a decision is made to reject h0 if xˉ≤980. find the level of this test.