A single server queuing system with a Poisson arrival rate and exponential service time has an average arrival rate of 13 customers per hour and an average service rate of 18 customers per hour. What is the probability that this system will contain 4 or more customers? O a. 0.2721 Ob 0.7279 OC. 0.6233 O d. 0.8035 A decision problem has the following three constraints: 25X + 32y 13. and 123X+ 41Y >= 6.5. The following is true for this problem: O a. Infeasible problem. O b. X = 0, Y = 41 is the only optimal solution O c. X=41, Y=-14 is the only optimal solution O d. Unbounded