The search for alternatives to oil as a major source of fuel and energy will inevitably bring about many environmental challenges. These challenges will require solutions to problems in such areas as strip mining and many others. Let us focus on one. If coal is considered as a major source of fuel and energy, we will have to consider ways to keep large amounts of sulfur dioxide (SO2) and particulates from getting into the air. This is especially important at large government and industrial operations. Here are some possibilities.
1. Build the smokestack extremely high.
2. Remove the SO2 and particulates from the coal prior to combustion.
3. Remove the SO2 from the gases after the coal is burned but before the gases are released into the atmosphere. This is accomplished by using a scrubber.
A new type of scrubber has been recently constructed and is set for testing at a power plant. Over a 15-day period, samples are obtained three times daily from gases emitted from the stack. The amounts of SO2 emissions (in pounds per million BTU) are given here:


a. Estimate the average amount of SO2 emissions during each of the three time periods using 95% confidence intervals.
b. Does there appear to be a significant difference in the average amounts of SO2 emissions over the three time periods?
c. Combining the data over the entire day, is the average amount of SO2 emissions using the new scrubber less than .145, the average daily value for the old scrubber?