a) The standard deviations of both populations are known, so use the z statistic; the significance level is given as 0.05, as this is an one-tailed test, the rejection region of 0.05 lies in the right tail of the distribution (the > in the H1 hypothesis indicates right tail). As the significance level of 0.05 is found in the t-distribution table, look up the value of z under infinity degrees of freedom (if the significance level given in the problem is not found in the t-distribution table, then look up the value in the z table). b) Calculate z (use the formula 11-2 on page 313 in the text) c) Compare the z critical value and the z calculated value to take a decision regarding Ho