The EPA Has Stipulated That the Pollution Standard Index (PSI)

Multiple Choice

The EPA has stipulated that the Pollution Standard Index (PSI) for clean air standards is to average no more than 100. A random sample of 9 days for the city of Acme showed PSI readings of 144, 85, 90, 120, 150, 105, 93, 130, and 115. The EPA wants to test to determine if Acme air is dirtier than the stipulated clean air standards. Assume the population of PSI readings is highly nonnormal and state the null hypothesis.

A) H₀: M_d ≥ 100
B) H₀: M_d ≤ 100
C) H₀: M_d ≠ 100
D) H₀: M_d > 100