Read the following passage carefully and answer the five questions that follows

An investigator designs an experiment to see the effect of illumination level and duration of visual signal on detectability of change in illumination in a dark room on 120 randomly selected sample of college going male students. She decided to use low and high levels of illumination and three levels of duration of stimulus as 30,50 and 70 milliseconds through an electric chronoscopic instrument. The investigator used separate group design for various combination of treatments. These participants were required to press a 'Yes' button if they detect the signal or 'No' button if they do not. Each participant was given a total of 50 trials within which 10 signals were randomly presented. Proportions of hits and false alarms was computed for each participant and were analysed to get answers to research questions.