Problem 10.16 (b,c,d) Consider a study comparing two medicines for infections severe bladder. The variable x is the length of time of establishment (in days). For The N1 = 15 patients who received medicine 1, we observed an average time of Establishment of x1 = 16.9 days. Average establishment time was x2 = 19.09 days For N2 = 18 patients who received medicine 2.

Suppose that the two settlement time populations are normally distributed. with equal variances. (b) Base yourself on the output of R and calculate the value of the standard deviation laid down.

> t.test(x1,x2,var.equal=TRUE) Two Sample t-test data: x1 and x2 t = -5.174, df = 31, p-value = 1.304e-05 alternative hypothesis: true difference in means is not equal to 0 95 percent confidence interval: -3.105940 -1.349615 sample estimates: mean of x mean of y 16.86667 19.09444

(c) Use the output of R obtained in (b). Give a 95% confidence interval for the difference between the average establishment time with medicine 1 and the time of average establishment with medicine 2. (d) Use the confidence interval in (c). Which medicine is best?