**UNIVERSITY EXAMINATIONS: 2014/2015**

**ORDINARY EXAMINATION FOR THE BACHELOR OF SCIENCE **

**IN INFORMATION TECHNOLOGY**

**BIT 2201 SIMULATION AND MODELING**

**DATE: APRIL, 2015 TIME: 2 HOURS**

**INSTRUCTIONS: Answer Question ONE and any other TWO**

**QUESTION ONE: 30 MARKS (COMPULSORY)**

a) It is not always possible to experiment and study with real systems hence the need for

modeling. Discuss three reasons why that is so. (3 marks)

b) Discuss five applications of simulation and modeling in real life (5 marks)

c) Using the mid- square method obtain the random variables using Z0= 1009 until the

cycle degenerates to zero. (7 marks)

d) Discuss any five desirable features of a good simulation software (5 marks)

e) Using the banking systems as an example describe the components of a discreteevent system. (10 marks)

**QUESTION TWO: 20 MARKS**

a) Every system exists with an environment. Activities in the system’s environment

cause changes in the state of the system. These activities are classified into two

categories: Endogenous and Exogenous. Differentiate between the two. (2 marks)

b) Discuss four reasons why it is necessary to use animation during the process of

modeling and simulation. (4 marks)

c) State and briefly explain four properties of a good arithmetic random number

generator. (4 marks)

d) Describe five common statistics included in the output report of a simulation

programming system. (10 marks)

**QUESTION THREE: 20 MARKS**

a) There are two fundamental types of animation; concurrent and post-processed

Differentiate between the two types of animation. (2 marks)

b) Describe the following terms giving examples from the communication systems.

(5 marks)

i) State of a System

ii) State Variables

iii) Entity

iv) Attribute

v) Activity

c) Discuss four drawbacks simulation and modeling. (4 marks)

d) Using the Linear Congruential Generator (LCG) with a=5, m=16, c=3 and seed Z0 = 7

to generate the first FIVE random variates on [0,1]. (5 marks)

e) Discuss the two short comings of the mid-square method as a random number

generator. (4 marks)

**QUESTION FOUR: 20 MARKS**

a) Define the terms verification and validation in the context of modeling. (4 marks)

b) Not all simulation and modeling exercises are a success. Discuss five common pitfalls

to successful simulation. (5 marks)

c) Consider a single server queuing system in the bank. The system starts at time t=0.

The arrival time of customers is: 0.4, 1.6, 2.1, 3.8, 4.0, 5.6, 5.8, and 7.2. The

departure times are: 2.4, 3.1, 3.3, 4.9, and 8.6. Time is in minutes. The first in first out

queuing discipline is followed. Simulate this system for six clients and estimate:

i) The expected average delay in the queue (3 marks)

ii) The expected average number of clients in the in the at any time t

(6 marks)

iii) The expected utilization of server. (2 marks)

**QUESTION FIVE: 20 MARKS**

a) Differentiate between the following types of models (6 marks)

i) Deterministic Vs Stochastic Models

ii) Discrete Models Vs Continuous Models

b) Discuss any five advantages of simulation (5 marks)

c) The table below shows the probability distribution of a container arrivals per day at

Mombasa port.

The offloading rate per day follows the probability distribution given below. NB:

Offloading is done on FCFS basis.

Offloading rate Probability

Suppose the following are the random numbers of arrivals and random numbers of

unloading.

Arrival Random No. 52, 06, 50, 88, 53, 30, 10, 47, 99, 37, 66, 91, 35, 32, 00

Offload Random No. 37, 63, 28, 02, 74, 35, 24, 03, 29, 60, 74, 85 90, 73, 59

Required: simulate a fifteen day analysis and determine:

i) The average number of container delayed (3 marks)

ii) The average number of arrivals per day (3 marks)

iii) The average number of containers offloaded each day (3 marks)