Q&A Hero

Q: Which of the following is not a component of the structure of a linear programming model? A. constraints B. decision variables C. parameters D. a goal or objective E. environmental uncertainty

Q: The linear optimization technique for allocating constrained resources among different products is: A. linear regression analysis. B. linear disaggregation. C. linear decomposition. D. linear programming. E. linear tracking analysis.

Q: Using the enumeration approach, optimality is obtained by evaluating every coordinate.

Q: When a change in the value of an objective function coefficient remains within the range of optimality, the optimal solution also remains the same.

Q: Nonbinding constraints are not associated with the feasible solution space; i.e., they are redundant and can be eliminated from the matrix.

Q: Every change in the value of an objective function coefficient will lead to changes in the optimal solution.

Q: In the range of feasibility, the value of the shadow price remains constant.

Q: Nonzero slack or surplus is associated with a binding constraint.

Q: The term range of feasibility refers to coefficients of the objective function.

Q: A shadow price indicates how much a one-unit decrease/increase in the right-hand-side value of a constraint will decrease/increase the optimal value of the objective function.

Q: The term range of optimality refers to a constraint's right-hand-side quantity.

Q: A change in the value of an objective function coefficient does not change the optimal solution.

Q: The simplex method is a general-purpose LP algorithm that can be used for solving only problems with more than six variables.

Q: If a single optimal solution exists to a graphical LP problem, it will exist at a corner point.

Q: A maximization problem may be characterized by all greater than or equal to constraints.

Q: A linear programming problem can have multiple optimal solutions.

Q: The value of an objective function decreases as it is moved away from the origin.

Q: The feasible solution space is the set of all feasible combinations of decision variables as defined by only binding constraints.

Q: The term isoprofit line means that all points on the line will yield the same profit.

Q: An objective function represents a family of parallel lines.

Q: Graphical linear programming can handle problems that involve any number of decision variables.

Q: The equation 3xy = 9 is linear.

Q: The equation 5x + 7y = 10 is linear.

Q: Profit maximization, like cost minimization, could be an objective of an LP problem, but neither would be an actual decision variable.

Q: Constraints limit the alternatives available to a decision maker; removing constraints adds viable alternative solutions.

Q: LP problems must have a single goal or objective specified.

Q: Linear programming techniques will always produce an optimal solution to an LP problem.

Q: The feasible solution space only contains points that satisfy all constraints.

Q: A bank of 10 machines requires regular periodic service. Machine running time and service time are both exponential. Machines run for an average of 44 minutes between service requirements, and service time averages six minutes per machine. What is the probability that a machine will have to wait for service with two operators? A. .654 B. .090 C. .346 D. .910 E. .016

Q: If a firm has reached the point at which further reducing waiting time is not economically feasible, reducing the ______________ is sometimes attractive. A. channels B. perceived service time C. capacity underload D. perceived waiting time E. system underutilization

Q: A multiple-channel system has customers arriving at an average rate of five per hour and an average service time of 40 minutes. The minimum number of servers for this system to be underloaded is: A. 2. B. 3. C. 4. D. 5. E. 6.

Q: A queuing system has four crews with three members each. The number of "servers" is: A. 3. B. 4. C. 7. D. 12. E. 1.

Q: An alternative strategy to increase the capacity of a service system is: A. reducing the number of arrivals. B. increasing variability. C. increasing the processing rate. D. reducing the number of servers. E. reducing the processing rate.

Q: A ________ is one way of reducing perceived waiting time. A. bonus B. gatekeeper C. reservation D. diversion E. number calling system

Q: When the waiting cost incurred by customers likely varies, an appropriate queuing model is: A. single channel, single phase. B. single channel, multiple phase. C. multiple channel, single priority. D. multiple channel, multiple phase. E. multiple channel, multiple priority.

Q: A single-channel queuing system has an average service time of 16 minutes per customer, which is exponentially distributed. The manager is thinking of converting to a system with a constant service time of 16 minutes. The arrival rate will remain the same. The effect will be to: A. increase utilization. B. decrease utilization. C. increase the average waiting time. D. decrease the average waiting time. E. not have any effect since the service time is unchanged.

Q: Which one of the following measures of system performance is a key measure with respect to customer satisfaction? A. average number of customers waiting in line B. system utilization C. average number of customers in the calling population D. probability of a server being busy E. capacity costs per hour

Q: A multiple-channel queuing system with a Poisson arrival rate and exponential service time has an average arrival rate of four customers per hour and an average service time of 18 minutes per customer. The minimum number of servers required to avoid an overloaded system is: A. 1. B. 2. C. 3. D. 4. E. 5.

Q: A single-bay car wash with a Poisson arrival rate and an exponential service time has cars arriving an average of 10 minutes apart, and an average service time of four minutes. The system utilization is: A. .24. B. .40. C. .67. D. 2.50. E. 1.25.

Q: Servers and channels are described with many acronyms except: A. M/P/S. B. M/M/1. C. M/D/1. D. M/M/S.

Q: As the ratio of arrival rate to service rate is increased, which of the following is likely? A. Customers move through the system in less time because utilization is increased. B. Customers move through the system more slowly because utilization is increased. C. Utilization is decreased because of the added strain on the system. D. The average number in the system decreases. E. There really is no change since arrival rates are offset by service rates.

Q: Little's law states that the number of people in a waiting line is the average customer arrival rate multiplied by the: A. average time in the system. B. average waiting time. C. service time minus the waiting time. D. average number in line. E. waiting time.

Q: The total cost curve: A. starts at zero and increases as service capacity increases. B. begins high and decreases as service capacity increases. C. starts high, declines, then increases again. D. remains relatively flat regardless of service capacity. E. starts at zero, increases rapidly, then declines slowly back to zero.

Q: Which of the following is not generally considered to be a measure of system performance in a queuing analysis? A. the average number waiting in line B. the average number in the system C. system utilization D. the cost of servers plus customer waiting cost E. average serving time

Q: In a _______ system, customers enter the waiting line, receive service, and leave. A. fast-track B. simulated C. queuing D. random E. nonrandom

Q: A single-channel queuing system has an average service time of eight minutes and an average time between arrivals of 10 minutes. The arrival rate is: A. 6 per hour. B. 7.5 per hour. C. 8 per hour. D. 10 per hour. E. 12.5 per hour.

Q: A single-phase queuing system is one which has a single: A. channel. B. server. C. customer being served. D. operation. E. waiting line.

Q: If a manager increases system utilization (assuming no change in the customer arrival rate) what happens to the customer waiting time? A. It increases exponentially. B. It increases proportionally. C. It decreases proportionally. D. It decreases exponentially. E. No change.

Q: A basic difference between infinite-source and finite-source queuing models is the: A. number of servers. B. average waiting time. C. arrival distribution. D. size of potential calling population. E. processing rate.

Q: The goal of queuing analysis is to minimize: A. the sum of customer waiting costs and capacity costs. B. the sum of customer waiting time and service time. C. capacity costs. D. customer waiting time. E. idle servers.

Q: Why is there waiting in an infinite-source queuing system? A. poor scheduling of servers B. slow service C. low utilization D. variability in arrival and service rates E. multiple-phase processing

Q: Although it is generally the case that service systems have enough capacity, waiting lines result when __________ exceeds capacity for periods of time. A. homogeneity B. variability C. price D. demand E. heterogeneity

Q: A customer growing frustrated with the wait and leaving the facility (without being served) is an example of: A. reneging. B. utilizing. C. balking. D. jockeying. E. departing.

Q: In which of these settings would one be least likely to encounter first-come service? A. a fast-food restaurant B. a doctor's office C. a hotel check-in operation D. an emergency room E. a check-out line

Q: Which of the following would tend to increase the difference between the actual time customers spent waiting and the perceived time spent waiting by those customers? (I) Lots of experience with the service on the part of customers (II) Anxiety on the part of customers (III) A pleasant physical environment for the customers A. I and II only B. I only C. II only D. III only E. I, II, and III

Q: The value of standardizing some or all of a service is demonstrated by the shorter wait times observed in models with: A. constant demand rates. B. finite queues. C. infinite sources. D. finite sources. E. constant service times.

Q: To reduce waiting times by actively managing system constraints, managers could consider: (I) using temporary workers. (II) shifting demand from high-demand periods to low-demand periods. (III) offering more service variety. (IV) discovering bottlenecks. A. I and III only B. I, II, and IV only C. III only D. II and IV only E. IV only

Q: Compared to a single-channel system with exponential service time, a single-channel system with a constant service time causes a reduction of 50 percent in the average number waiting in line.

Q: Queue discipline requires a security presence to maintain order.

Q: All infinite-source queuing models require the system utilization to be less than 1.0.

Q: To reduce the average number waiting in line, it is important to increase utilization.

Q: In an infinite-source model, the system utilization is the ratio of the arrival rate to the service capacity.

Q: In an infinite-source model, the average time in line is equal to the average number in line divided by the arrival rate.

Q: In an infinite-source model, the average number being served is equal to the ratio of the arrival rate to the service rate.

Q: The queuing models discussed in the text apply only to steady-state conditions. Steady state exists only when customers arrive at a steady rate; that is, without any variability.

Q: An approach to reducing the variability in processing times might include greater standardization.

Q: For a system that has a low utilization ratio, decreasing service capacity slightly will have only negligible effect on customer waiting time.

Q: According to Little's law, the number of people in line depends on the time of day that they arrive.

Q: The goal of queuing analysis is to balance the cost of providing a level of service capacity with the possible loss of business due to customers leaving the line or refusing to wait.

Q: The most commonly used queuing models assume that the arrival rate can be described by a Poisson distribution.

Q: A single-server, variable-service-time system is known as an M/D/1 system.

Q: A dental office with two professionals (one dentist, one hygienist) who work together as a team would be an example of a multiple-channel system.

Q: A multiple-channel system assumes that each server will have its own waiting line, and line changing is not permitted.

Q: The point that minimizes total queuing system costs is that point where waiting costs and capacity costs are equal.

Q: In a theme park like Disney world, reservation systems are a win-lose situation since only those holding reservations are satisfied.

Q: The cost of customer waiting is easy to estimate, the number waiting multiplied by the wait cost per minute.

Q: The goal of waiting-line management is to eliminate customer waiting lines.

Q: A system has one service facility that can service 10 customers per hour. The customers arrive at a variable rate, which averages six per hour. Since there is excess capacity, no waiting lines will form.

Q: Waiting lines occur even in underloaded systems because of variability in service rates and/or arrival rates.

Q: A manager assembled the following information about an infinite-source waiting line system: five servers, an arrival rate of six per hour, and a service time of 20 minutes. The manager has determined that the average number of customers waiting for service is .04. Determine each of the following: (A) the system utilization (B) the average waiting time in line in minutes (C) the average time in the system (D) the average number in the system