Among the data collected for the World Health Organization air quality monitoring project is a measure of suspended particles in μg/m3. Let X and Y equal the concentration of suspended particles in μg/m3 in the city center (commercial district) for Melbourne and Houston, respectively. Using n = 13 observations of X and m = 16 observations of Y , we test 
(a) Define the test statistic and critical region, assuming that the unknown variances are equal. Let α = 0.05.
