Dear users How can I solve these two problems by SAS software. 1.   A normally distributed random variable has an unknown mean Pand a known variance V2= 9. Find the sample size required to construct a 95 percent confidence interval on the mean, that has total width of 1.0.    2. A new filtering device is installed in a chemical unit. Before its installation, a random sample yielded the following information about the percentage of impurity: y1= 12.5, S12=101.17   (variance S1), and n1= 8. After installation, a random sample yielded y2= 10.2, S22= 94.73  (variance S2)   , n2= 9. (a) Can you concluded that the two variances are equal? Use D= 0.05. (b) Has the filtering device reduced the percentage of impurity significantly? Use D= 0.05.   Best regards ... View more