on street AB three traffic ligts connected . let i be the index of the ith traffic light & Ti is the waiting time behind the ith trafffic light. on average the waiting time for both the ith traffic light is i minutes. What is the appropriate prob distribution to model Ti. find the prob that that the ti id grester than 30 seconds. What is the prob model of T1+T2 if waiting times are independent (specifying the parameter model). what is the expectation and standard deviation of waitng time on street AB ?