The following is a control chart for the average number of minor errors in 22 service reports. a. Calculate the observed mear, expected mean, standard deviation and z value for the modlan and upldown test. Use z=+12 to compare your 2 test scores. (Negative amounts should be indicated by a minus sign. Round your answers to 2 decimal places.) b.Boved on your calculation conclude whether the test is randors or non-random