Question

(b) The investigators were worried that the reduction in pollution was only temporary- people using stoves carefully and following all recommendations correctly at first but becoming less concerned as years went by. A simple random sample of pollution data was collected for the following year (the second year after the stove replacements). The results are as follows:

19.46, 15.98, 15.79, 16.32, 13.49, 12.44, 8.40, 10.02, 11.08, 21.46, 20.57, 19.64, 10.75, 20.36, 14.59, 17.64, 11.75, 13.12, 14.85, 16.91

Are the pollution rates for the second year after the stove replacement program different than those from the first year? Use a = 0.05. You may assume the population is normal.

First year data:

A simple random sample of measurements of the total carbon in the air was recorded for various days during the first winter after the stoves were replaced. The results are as follows:

17.73, 17.87, 18.75, 15.64, 12.46, 9.66, 14.73, 13.23, 17.08, 15.86, 17.27, 10.21, 11.47, 9.21, 13.48, 7.795, 21.20, 15.65, 13.51, 9.94

Answer 1