A psychologist interested in animal learning conducts an experiment to determine the effect of adrenocorticotropic hormone (ACTH) on avoidance learning. Twenty 100-day-old male rats are randomly selected from the university vivarium for the experiment. Of the 20 chosen rats, 10 randomly chosen rats receive injections of ACTH 30 minutes before being placed in the avoidance situation. The other 10 rats received placebo injections. The number of trials for each animal to learn the task are listed below.Do NOT assume a normal distribution,and use ?=0.05 to answer the questions below:

\f