A copper 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 = 140 ppm. The sample mean arsenic content X¯¯¯ of 95 copper specimens will be computed, and the null hypothesis H0: μ ≥ 1030 will be tested against the alternate H1: μ < 1030. For what values of X¯¯¯ should H0 be rejected so that the power of the test will be 0.9 when the true mean content is 985? Round the answer to two decimal places.

The rejection region should be X¯¯¯ ≤