"time headway" in traffic flow is the elapsed time between the time that one car finishes passing a fixed point and the instant that the next car begins to pass that point. let x = the time headway for two randomly chosen consecutive cars on a freeway during a period of heavy flow. the pdf of x is the following.

f(x) =
0.15e−0.15(x − 0.5) x ≥ 0.5
0 otherwise

(a) what is the probability that time headway is at most 6 sec?