UNIVERSITY EXAMINATIONS: 2010/2011
SECOND YEAR STAGE EXAMINATION FOR THE DEGREE OF BACHELOR
OF SCIENCE IN INFORMATION TECHNOLOGY
BIT 2201: SIMULATION AND MODELLING
DATE: AUGUST 2011 TIME: 2 HOURS
INSTRUCTIONS: Answer question ONE and any other TWO questions
Question One
a) Explain the term Simulation. (3 Marks )
b) Using appropriate examples identify four main types of system. (8 Marks )
c) Define an operating system as used in simulation and modeling. List the four specific functions of
operating system. (4 marks)
d) i) Many operating systems are complex. Explain. (3 marks)
ii) What are the effects of dynamic complexity in a system? (3 Marks)
e) 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)
f) List the three main simulation programming tasks. (3 Marks)
Question Two
a) Discuss the factors that should be considered in selecting a simulation language. (10 Marks)
b) i) Outline FIVE characteristics of a good random number generator. (5 Marks)
ii) Use a mixed linear congruential random number generator with a=67, m=31, c=17 and seed X0
= 117 to generate the first FIVE random variates on [0,1]. (5 Marks)
Question Three
a) Describe five common statistics included in the output report of a simulation programming system.
(10 Marks)
b) The time taken to process print jobs by a computer is given by:
Time No.
0-4 3
4-8 8
8-10 15
10-12 19
12-14 9
14-20 6
Test at 5% significant level whether this time follows an exponential distribution. (10 Marks)
Question Four
a) Consider a simple server queuing system that starts at time t=0. The arrivals occur at times 1.2, 1.8,
2.6, 3.8, 6.0, 6.2, 7.0, 7.5, 8.6 and 9.2. Departures occur at times 3.0, 4.2, 4.9, 5.6 and 10. Time is
in minutes. Simulate this system until when the sixth client enters service and estimate:
i) The average delay in the waiting line (6 Marks)
ii) The average number of clients in the waiting line at any time t (10 Marks)
iii) The server utilization rate. (4 Marks)
Question Five
a) Define the following concepts:
i) Simulation (2 Marks)
ii) Arrival pattern (2 Marks)
iii)System State (2 Marks)
iv)System Image (2 Marks)
v) Simulation Algorithm (2 Marks)
b) Discuss the “build model right-build right model” philosophy of model verification and validation.
(6 Marks)
c) Explain why animation is appropriate in explaining the behavior of a model when it is completed.
(4 Marks)
