A local charity has been given a grant to serve free meals to the homeless in its community, but it is worried that its program might be exploited by nearby college students, who are always on the lookout for a free meal.  Both a homeless person and a college student receive a payoff of 10 for a free meal.  The cost of standing in line for the meal is t2/320 for a homeless person and t2/160 for a college student, where t is the amount of time in line measured in minutes.  Assume that the staff of the charity cannot observe the true type of those coming for free meals. 

a.  What is the minimum wait time t that will achieve separation of types? 

b.  After a while, the charity finds that it can sucessfully identify and turn away college students half of the time.  College students who are turned away receive no free meal and, further, incur a cost of 5 for their time and embarassment.  Will the partial identification of college students reduce or increase the answer in part (a)/  Explain.