Flow meters are installed in urban sewer systems to measure the flows through the pipes. In dry weather conditions (no rain) the flows are generated by waste-water from households and industries, together with some possible drainage from water stored in the topsoil from previous rainfalls. In a study of an urban sewer system, the following values were obtained for flow rates during dry weather conditions:

423.6, 487.3, 453.2, 402.9, 483.0, 477.7, 442.3, 418.4, 459.0 Assume that the flow rates are normally distributed.

(e) 3 points Test the hypothesis (two-sided test) that the mean flow rate is equal to 440. Use a significance level of 5%. What can you conclude on the basis of this test? (f) 3 points Test the hypothesis (one-sided upper-tailed test) that the standard deviation of the flow rate is equal to 28. Use a significance level of 5%. What can you conclude on the basis of this test?