UNIVERSITY EXAMINATIONS: 2013/2014
ORDINARY EXAMINATION FOR THE BACHELOR OF SCIENCE
IN INFORMATION TECHNOLOGY
BIT 2201 SIMULATION AND MODELING
(DAY)
DATE: APRIL, 2014 TIME: 2 HOURS
INSTRUCTIONS: Answer Question ONE and any other TWO
QUESTION ONE
a) Discuss the two short comings of the mid-square method as generator of random
numbers. [4 Marks]
b) Using the Linear Congruential Generator (LCG) with a=67, m=31, c=17 and seed Z0
= 117 to generate the first FIVE random variates on [0,1]. [6 Marks]
c) Using appropriate examples identify four main types of systems. [6 Marks]
d) Simulation models are not the only models that can be used for understanding and
improving the real world. There exist other modeling approaches. Why would
simulation be used in preference to these other modeling approaches? [6 Marks]
e) With the help of well labeled diagrams illustrate and describe the four types of queues
that exist giving common place examples. [8 Marks]
QUESTION TWO
a) Describe five common statistics included in the output report of a simulation
programming system. [10 Marks]
The table below shows the probability distribution of a barges arriver per day at a port.
The unloading rate per day follows the probability distribution given below. NB:
unloading is done on FCFS basis.
Suppose the following are the random numbers of arrivals and random numbers of
unloading.
Arrival Random No. 53, 07, 51, 82, 50, 35, 12, 57, 99, 27, 56, 93, 35, 34, 00, 22, 31
Unload Random No. 35, 66, 38, 12, 54, 75, 34, 05, 19, 70, 64, 85 90, 73, 59 61, 43
Required: determine: simulate a seventeen day analysis and determine:
i. The average number of barges delayed [4 Marks]
ii. The average number of arrivals per day [3 Marks]
iii. The average number of barges offloaded each day [3 Marks]
QUESTION THREE
a) Define the terms verification and validation in the context of modeling. [4 Marks]
b) Dynamic systems have a state that is ever changing as a result of changes in state
variables. In your own understanding describe the terms system, system state, and
state variable [6 Marks]
c) Not all simulation and modeling exercises are a success. Discuss five common pitfalls
to successful simulation. [5 Marks]
d) Describe the factors that should be considered in selecting a simulation language.
[5 Marks]
QUESTION FOUR
a) State and briefly explain four properties of a good arithmetic random number
generator. [4 Marks]
b) Consider a single server queuing system. The system starts at time t=0. The arrival
time of customers is: 0.8, 1.4, 2.7, 3.2, 3.8, 8.0, 8.6, 9.0, 9.2, and 9.8. The departure
times are: 2.2, 4.0, 5.0, 6.2, and 10.0. Time is in minutes. The first in first out queuing
discipline is followed. Simulate this system for six clients and estimate:
i) The average delay in the waiting line [3 Marks]
ii) The average number of clients in the waiting line at any time t
[5 Marks]
iii) The expected utilization of server. [2 Marks]
c) Differentiate between the following types of models [6 Marks]
i. Deterministic Vs Stochastic Models
ii. Discrete Models Vs Continuous Models
QUESTION FIVE
a) Describe all the components found in most discrete event simulation models.
[10 Marks]
b) Using the mid- square method obtain the random variables using Z0= 7182 until the
cycle degenerates to zero. [10 Marks]
