Please solve B

128. [Strait, P172, #4] The time interval (measured in minutes) between cars arriving at a certain toll booth is an exponential random variable with parameter 6 = 2. Find the probability that (a) there will be a wait of at least 3 minutes between the rst and the second cars arriving at this toll booth on a given day; (b) there will be a wait of at least 3 minutes between each of the rst 6 cars arriving at this toll booth on a given day