Our environment is very sensitive to the amount of ozone in the upper atmosphere. The level of ozone normally found is 6.3 parts/million (ppm). A researcher believes that the current ozone level is at an excess level. The mean of 870 samples is 6.4 ppm. Assume the variance is known to be 1.00. Does the data support the claim at the 0.1 level? Step 4 of 5: Enter the decision rule.