1. In an experiment designed to study the effects of illumination level on task performance, subjects were required to insert a fine-tipped probe into the eyeholes of ten needles in rapid succession both for a low light level with a black background and a higher level with a white background. Each data value is the time (in seconds) required to complete the task. Subject 1 2 3 4 5 6 7 8 9 Black 26 27 32 26 21 41 25 23 27 White 18 21 23 20 20 25 17 16 25