A modification has been made to the process for producing a certain type of “time-zero” film (film that begins to develop as soon as a picture is taken). Because the modification involves extra cost, it will be incorporated only if sample data strongly indicates that the modification has decreased true average developing time by more than 1 second. Assuming that the developing-time distributions differ only with respect to location, if at all, use the Wilcoxon rank-sum test at level .05 on the data just above Exercise 13 to test the appropriate hypotheses.

Ha H0 : m1 . m2 : m1 5 m2 Original Process 8.6 5.1 4.5 5.4 6.3 6.6 5.7 8.5 Modified Process 5.5 4.0 3.8 6.0 5.8 4.9 7.0 5.7