Sulfur dioxide is a toxic gas, has a distinct, pungent odor, and contributes to acid rain and changes in climate. It is usually released into the atmosphere by volcanoes, but sulfur dioxide is also...

Sulfur dioxide is a toxic gas, has a distinct, pungent odor, and contributes to acid rain and changes in climate. It is usually released into the atmosphere by volcanoes, but sulfur dioxide is also emitted from coal-fired electricity-generating plants. Independent random times at four coal-fired power plants in the United States were selected, and the sulfur dioxide emission rate was measured (in lb/MWh) for each. Summary statistics are given in the following table. Use this information with a 5 0.01 to test the null hypothesis of no difference in population mean sulfur dioxide emission rates.5