COB 291 EXAM 3 QUESTIONS AND
ANSWERS
Which type of queuing system are you likely to encounter at an ATM? - Answer- Single
waiting line, single service station.
The server utilization U in an M/M/s system is always the same as the traffic intensity. -
Answer- True
The decision to balk at entering a queuing system can be made by the customer or the
system. - Answer- True
The parameter λ in an exponential distribution can be interpreted as a: - Answer- rate
What is the formula for the probability of x arrivals, p(x), under a Poisson distribution
with arrival rate λ? - Answer- λ^x*e^-λ/x!
Server utilization is the: - Answer- fraction of time a typical server is busy
In queuing systems with a finite number of customers allowed, there is no need to
require that the traffic intensity be less than 1 to ensure stability. - Answer- True
Which type of queuing system are you likely to encounter at a grocery store? - Answer-
Multiple waiting lines, multiple service stations.
A Poisson distribution shape can be described as - Answer- skewed to the right.
A company has recorded the following list of service rates (customers/hour) for one of
its servers. What is the mean service time for this server?
Customers / hour: 4, 4, 5, 6, 5, 4, 3, 4, 3, 5, 5, 6 - Answer- 13.3 min
(4+4+5+6+5+4+3+4+3+5+5+6)/12=4.5
The mean and standard deviation of an exponential distribution are both equal to the
parameter λ. - Answer- False
What are some of the important issues defining types of arrivals in a queuing system? -
Answer- - whether customers will wait in line or not
- Whether customers are all essentially alike or are in separate priority classes.
, - Whether customers arrive one at a time or in batches.
In a process where interarrival times are exponentially distributed, the time since the
last arrival is irrelevant. - Answer- True
Which of the following is a reason to employ queuing theory? - Answer- To reduce
customer wait time in line
The exponential distribution is: - Answer- heavily right-skewed
A barber shop has one barber, a Poisson arrival rate and exponentially distributed
service times. What is the Kendall notation for this system? - Answer- M/M/1
Joe's Copy Center has 10 copiers. They break down at a rate of 0.02 copiers per hour
and are sent to the service facility. What is the average arrival rate of broken copiers to
the service facility? - Answer- 0.2 = 10 * 0.02
To find steady-state values for the M/M/S queuing system, which of the following
statements must be true about the arrival rate? - Answer- λ < s μ
The amount of time a customer spends with the server is referred to as - Answer-
service time
The states of nature are defined so that they are _____. This means that at least one
state of nature must occur at a given time for a chance event. - Answer- collectively
exhausted
Suppose that, for a given decision alternative, the payoffs are (10, 20, 30) with
respective probabilities of (0.2, 0.3 and 0.5). The expected payoff for this alternative is: -
Answer- 23 = (10*0.2) + (20*0.3) + (30*0.5)
New information obtained through research or experimentation that enables an updating
or revision of the state-of-nature probabilities is known as _____. - Answer- sample
information
_____ refer to the probabilities of the states of nature after revising the prior
probabilities based on sample information. - Answer- Posterior probabilities
We can apply a process known as ______ to a decision tree to determine the decision
with the largest EMV. - Answer- Rolling back.
A measure of the outcome of a decision such as profit, cost, or time is known as a
_____. - Answer- payoff
ANSWERS
Which type of queuing system are you likely to encounter at an ATM? - Answer- Single
waiting line, single service station.
The server utilization U in an M/M/s system is always the same as the traffic intensity. -
Answer- True
The decision to balk at entering a queuing system can be made by the customer or the
system. - Answer- True
The parameter λ in an exponential distribution can be interpreted as a: - Answer- rate
What is the formula for the probability of x arrivals, p(x), under a Poisson distribution
with arrival rate λ? - Answer- λ^x*e^-λ/x!
Server utilization is the: - Answer- fraction of time a typical server is busy
In queuing systems with a finite number of customers allowed, there is no need to
require that the traffic intensity be less than 1 to ensure stability. - Answer- True
Which type of queuing system are you likely to encounter at a grocery store? - Answer-
Multiple waiting lines, multiple service stations.
A Poisson distribution shape can be described as - Answer- skewed to the right.
A company has recorded the following list of service rates (customers/hour) for one of
its servers. What is the mean service time for this server?
Customers / hour: 4, 4, 5, 6, 5, 4, 3, 4, 3, 5, 5, 6 - Answer- 13.3 min
(4+4+5+6+5+4+3+4+3+5+5+6)/12=4.5
The mean and standard deviation of an exponential distribution are both equal to the
parameter λ. - Answer- False
What are some of the important issues defining types of arrivals in a queuing system? -
Answer- - whether customers will wait in line or not
- Whether customers are all essentially alike or are in separate priority classes.
, - Whether customers arrive one at a time or in batches.
In a process where interarrival times are exponentially distributed, the time since the
last arrival is irrelevant. - Answer- True
Which of the following is a reason to employ queuing theory? - Answer- To reduce
customer wait time in line
The exponential distribution is: - Answer- heavily right-skewed
A barber shop has one barber, a Poisson arrival rate and exponentially distributed
service times. What is the Kendall notation for this system? - Answer- M/M/1
Joe's Copy Center has 10 copiers. They break down at a rate of 0.02 copiers per hour
and are sent to the service facility. What is the average arrival rate of broken copiers to
the service facility? - Answer- 0.2 = 10 * 0.02
To find steady-state values for the M/M/S queuing system, which of the following
statements must be true about the arrival rate? - Answer- λ < s μ
The amount of time a customer spends with the server is referred to as - Answer-
service time
The states of nature are defined so that they are _____. This means that at least one
state of nature must occur at a given time for a chance event. - Answer- collectively
exhausted
Suppose that, for a given decision alternative, the payoffs are (10, 20, 30) with
respective probabilities of (0.2, 0.3 and 0.5). The expected payoff for this alternative is: -
Answer- 23 = (10*0.2) + (20*0.3) + (30*0.5)
New information obtained through research or experimentation that enables an updating
or revision of the state-of-nature probabilities is known as _____. - Answer- sample
information
_____ refer to the probabilities of the states of nature after revising the prior
probabilities based on sample information. - Answer- Posterior probabilities
We can apply a process known as ______ to a decision tree to determine the decision
with the largest EMV. - Answer- Rolling back.
A measure of the outcome of a decision such as profit, cost, or time is known as a
_____. - Answer- payoff
