UNIVERSITY EXAMINATIONS: 2012/2013
EXAMINATION FOR THE BACHELOR OF SCIENCE IN
INFORMATION TECHNOLOGY
BIT 2201 SIMULATION AND MODELLING
DATE: AUGUST, 2013 TIME: 2 HOURS
INSTRUCTIONS: Answer Question ONE and Any Other TWO Questions
QUESTION ONE
a) Define the following terms as used in simulation and modeling:
i) operating system
ii) system image
iii) state variable
iv) simulation algorithm
v) Event list (10 Marks)
b) Differentiate the following terms:
i) Point estimate and interval estimate
ii) Verification and validation (8 Marks)
c) What are the effects of dynamic complexity in a system? (3 Marks)
d) Use a mixed linear congruential random number generator with a=11, m=313, c=17
and seed X0 = 117 to generate the first FIVE random variates on[0,1] (5 Marks)
e) The purpose for modeling can also have a functional level. List any FOUR levels to
which simulation and modeling has been applied. (4 Marks)
QUESTION TWO
a) List and discuss any FOUR disadvantages of simulation. (12 Marks)
b) Briefly explain the FOUR principles used in modeling. (8 Marks)
QUESTION THREE
a) Consider a single server queuing system. The system starts at time t=0. The arrival
times are: 1.1, 1.2, 1.3, 1.4, 4.0, 4.2, 5.5, 5.6, 6.5, 6.8, 8.0, 8.7, and 9.0. The departure
times are: 2.0, 2.4, 3.0, 3.6, 4.8, 7.5 and 10. Time is in minutes.
Simulate this system until the eighth client starts service and hence estimate;
i) Expected average delay of a customer in the waiting line
ii) Expected average number of customers in the waiting line
iii) Expected utilization of Server. (12 Marks)
b) Explain clearly how one can build a valid and credible model. (8 Marks)
QUESTION FOUR
a) Most simulation programming systems include a report generator to print out
statistics gathered during the run. Describe any FIVE common required statistics,
which are usually included in the output. (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 FIVE
a) Among the most compelling reasons for using simulation are the benefits gained by
managers. Explain any THREE benefits. (9 Marks)
b) Explain why animation is appropriate in explaining the behavior of a model when it is
completed. (3 Marks)
c) Describe any FOUR factors that should be considered when selecting simulation
software. (8 Marks)
