The article “Effects of Aerosol Species on Atmospheric Visibility in Kaohsiung City, Taiwan” (C. Lee, C.Yuan, and J. Chang, Journal of Air and Waste Management, 2005:1031–1041) reported that for a...

The article “Effects of Aerosol Species on Atmospheric Visibility in Kaohsiung City, Taiwan” (C. Lee, C.Yuan, and J. Chang, Journal of Air and Waste Management, 2005:1031–1041) reported that for a sample of 20 days in the winter, the mass ratio of fine to coarse particles averaged 0.51 with a standard deviation of 0.09, and for a sample of 14 days in the spring the mass ratio averaged 0.62 with a standard deviation of 0.09. Let μ1 represent the mean mass ratio during the winter and let μ2 represent the mean mass ratio during the summer. It is desired to test H0:μ2 − μ1 = 0 versus H1:μ2 − μ1 ≠ 0

a. Someone suggests that since the sample standard deviations are equal, the pooled variance should be used. Do you agree? Explain.

b. Using an appropriate method, perform the test.