ISYE 6644 - FINAL PREP2 EXAM
QUESTIONS WITH DETAILED
ANSWERS
If f(x, y) = cxy for all 0 < x < 1 and 1 < y < 2, where c is whatever value makes this thing
integrate to 1, then X and Y are independent random variables - ANSWERSTRUE.
(Because f(x, y) = a(x)b(y) factors nicely, and there are no funny limits.)
In our Arena Call Center example, it was possible for entities to be left in the system
when it shut down at 7:00 p.m. (even though we stopped allowing customers to enter
the system at 6:00 p.m.). - ANSWERSTRUE — because of the small chance that a
callback will occur.
An entity can be scheduled to visit the same resource twice, with different service time
distributions on the two visits! - ANSWERSTRUE
Arena has a built-in Input Analyzer tool that allows for the fitting of certain distributions
to data. - ANSWERSTRUE
The Kolmogorov-Smirnov test can be used both to see (i) if data seem to fit to a
particular hypothesized distribution and (ii) if the data are independent. -
ANSWERSFALSE. (It's just a goodness-of-fit test.)
Welch's method is a graphical technique to estimate truncation (initialization bias) points
for steady-state simulation. - ANSWERSTRUE
If you are using a ranking-and-selection procedure and two competitors happen to fall
within the indifference-zone, then you don't really care too much which one you end up
selecting. - ANSWERSTRUE. That's why it's called the IZ!
TRUE or FALSE? Sequential ranking-and-selection procedures are designed to stop
early if one alternative seems to be way out in front of the others. - ANSWERSTRUE
Suppose, when designing a ranking-and-selection procedure, you have decided to
increase the desired probability of correct selection compared to a previous run of the
procedure. What can you expect? (a) Sample sizes that are about the same
(b) Larger sample sizes
(c) Somewhat lower achieved Pr(CS)
(d) A larger indifference zone
(e) Lower confidence in your selection - ANSWERSb
, In Arena, you can use a single DECIDE module to route customers to that one of four
servers having the smallest queue. - ANSWERSTRUE
TRUE or FALSE? In Arena, you can use the expression EXPO(3) to generate
exponential interarrival times having a mean of 1/3. - ANSWERSFALSE. The mean of
an EXPO(3) is 3.
TRUE or FALSE? In Arena, an alternative expression to generate exponential
interarrival times having a mean of 1/3 is -(1/3)*LN(UNIF(0,1)) - ANSWERSTRUE. This
is the Inverse Transform Method to generate an observation coming from Exp(λ = 3).
TRUE or FALSE? In Arena, it is possible to set the maximum capacity of a queue from
within a SEIZE module. - ANSWERSFALSE. It is only possible to set a maximum queue
capacity from within a QUEUE block found in the Blocks template. 2
TRUE or FALSE? In Arena, the expression NORM(-1,2)+NORM(3,2) has the same
distribution as the expression NORM(2,4) - ANSWERSFALSE. The above expression
evaluates to NORM(2,√ 8) since, in Arena, NORM(x,2) corresponds to a normal random
variate with a mean of x and a standard deviation of 2; so the variance of this random
variable is 22 = 4.
TRUE or FALSE? In Arena, it is only possible to use one resource at a time in a
PROCESS module. - ANSWERSFALSE
TRUE or FALSE? In Arena, once an entity is defined, it is not possible to change the
priority in which it gets processed by a resource. - ANSWERSFALSE
TRUE or FALSE? In Arena, it is not possible to use a single RELEASE module to
release multiple different resources - ANSWERSFALSE. We observed this in the
ReleaseHospitalRoomLater demo in HW7
What is the distribution given by the Arena expression UNIF(1,2)+UNIF(1,2)? -
ANSWERSTria(2,3,4).
An Arena ASSIGN module can be used to assign values to attributes and variables -
ANSWERSTRUE
TRUE or FALSE? In Arena, there are several ways to terminate a simulation, for
example, when a given simulation run length has been reached, or when a given
number of entities have been created, or when a specific stopping criterion as be met. -
ANSWERSTRUE
Suppose X is a discrete random variable that can take on four possible values: −0.1, 0,
2, and 4. The associated probabilities are, respectively: 0.3, 0.1, 0.2, and 0.4. Find an
expression in Arena to generate one observation coming from this p.m.f. -
ANSWERSDISC(0.3, −0.1, 0.4, 0, 0.6, 2, 1, 4)
QUESTIONS WITH DETAILED
ANSWERS
If f(x, y) = cxy for all 0 < x < 1 and 1 < y < 2, where c is whatever value makes this thing
integrate to 1, then X and Y are independent random variables - ANSWERSTRUE.
(Because f(x, y) = a(x)b(y) factors nicely, and there are no funny limits.)
In our Arena Call Center example, it was possible for entities to be left in the system
when it shut down at 7:00 p.m. (even though we stopped allowing customers to enter
the system at 6:00 p.m.). - ANSWERSTRUE — because of the small chance that a
callback will occur.
An entity can be scheduled to visit the same resource twice, with different service time
distributions on the two visits! - ANSWERSTRUE
Arena has a built-in Input Analyzer tool that allows for the fitting of certain distributions
to data. - ANSWERSTRUE
The Kolmogorov-Smirnov test can be used both to see (i) if data seem to fit to a
particular hypothesized distribution and (ii) if the data are independent. -
ANSWERSFALSE. (It's just a goodness-of-fit test.)
Welch's method is a graphical technique to estimate truncation (initialization bias) points
for steady-state simulation. - ANSWERSTRUE
If you are using a ranking-and-selection procedure and two competitors happen to fall
within the indifference-zone, then you don't really care too much which one you end up
selecting. - ANSWERSTRUE. That's why it's called the IZ!
TRUE or FALSE? Sequential ranking-and-selection procedures are designed to stop
early if one alternative seems to be way out in front of the others. - ANSWERSTRUE
Suppose, when designing a ranking-and-selection procedure, you have decided to
increase the desired probability of correct selection compared to a previous run of the
procedure. What can you expect? (a) Sample sizes that are about the same
(b) Larger sample sizes
(c) Somewhat lower achieved Pr(CS)
(d) A larger indifference zone
(e) Lower confidence in your selection - ANSWERSb
, In Arena, you can use a single DECIDE module to route customers to that one of four
servers having the smallest queue. - ANSWERSTRUE
TRUE or FALSE? In Arena, you can use the expression EXPO(3) to generate
exponential interarrival times having a mean of 1/3. - ANSWERSFALSE. The mean of
an EXPO(3) is 3.
TRUE or FALSE? In Arena, an alternative expression to generate exponential
interarrival times having a mean of 1/3 is -(1/3)*LN(UNIF(0,1)) - ANSWERSTRUE. This
is the Inverse Transform Method to generate an observation coming from Exp(λ = 3).
TRUE or FALSE? In Arena, it is possible to set the maximum capacity of a queue from
within a SEIZE module. - ANSWERSFALSE. It is only possible to set a maximum queue
capacity from within a QUEUE block found in the Blocks template. 2
TRUE or FALSE? In Arena, the expression NORM(-1,2)+NORM(3,2) has the same
distribution as the expression NORM(2,4) - ANSWERSFALSE. The above expression
evaluates to NORM(2,√ 8) since, in Arena, NORM(x,2) corresponds to a normal random
variate with a mean of x and a standard deviation of 2; so the variance of this random
variable is 22 = 4.
TRUE or FALSE? In Arena, it is only possible to use one resource at a time in a
PROCESS module. - ANSWERSFALSE
TRUE or FALSE? In Arena, once an entity is defined, it is not possible to change the
priority in which it gets processed by a resource. - ANSWERSFALSE
TRUE or FALSE? In Arena, it is not possible to use a single RELEASE module to
release multiple different resources - ANSWERSFALSE. We observed this in the
ReleaseHospitalRoomLater demo in HW7
What is the distribution given by the Arena expression UNIF(1,2)+UNIF(1,2)? -
ANSWERSTria(2,3,4).
An Arena ASSIGN module can be used to assign values to attributes and variables -
ANSWERSTRUE
TRUE or FALSE? In Arena, there are several ways to terminate a simulation, for
example, when a given simulation run length has been reached, or when a given
number of entities have been created, or when a specific stopping criterion as be met. -
ANSWERSTRUE
Suppose X is a discrete random variable that can take on four possible values: −0.1, 0,
2, and 4. The associated probabilities are, respectively: 0.3, 0.1, 0.2, and 0.4. Find an
expression in Arena to generate one observation coming from this p.m.f. -
ANSWERSDISC(0.3, −0.1, 0.4, 0, 0.6, 2, 1, 4)
