43. In an experiment designed to study the effects of illumination level on task performance ( Performance of Complex Tasks Under Different Levels of Illumination, J. Illuminating Engrg., 1976: 235—242), subjects were required to insert a ne-tipped probe into the eyeholes of ten needles in rapid succession both for a lowlight level with a black background and a higher level with a white background. Each data value is the time (sec) required to complete the task.

Subject 1 2 3 4 5 Black 25.85 28.84 32.05 25.74 20.89 White 18.23 20.84 22.96 19.68 19.50 Subject 6 7 8 9 Black 41.05 25.01 24.96 27.47 White 24.98 16.61 16.07 24.59 Does the data indicate that the higher level of illumination yields a decrease of more than 5 sec in true average task completion time? Test the appropriate hypotheses using the P-value approach.