6.A single server queuing system with a Poisson arrival rate and exponential service time has an average arrival rate of 5 customers per hour and an average service rate of 7 customers per hour. The probability of 4 customers in the system is :

a.

0.2857

b.

0.9256

c.

0.07437

d.

0.7397

7.A Linear programming problem has the following three constraints: 48X + 12Y <= 576; 21X + 6Y= 126; and 7X - Y <= -21 . The objective function is Min 5X + 49Y . What combination of X and Y will yield the optimum solution for this problem?

a.

6 , 0

b.

unbounded problem

c.

0 , 21

d.

0 , 21

e.

infeasible problem