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QUESTION 1 [125 MARKS]
(a) Define the Linear Congruential Generator (LCG), and using a seed 2, multiplier 15,
increment 3 and modulus 85, obtain the sequence of pseudo-random numbers using the
LCG.
(33 Marks)
Is there cycling? (YES/NO). If so, when does it occur?
(3 Marks)
(b) A data communication line delivers a block of information every 10 microseconds (µs). A
decoder checks each block for errors and corrects the errors if necessary. It takes 1 µs to
determine whether the block has any errors. If the block has one error it takes 5µs to
correct it and if it has more than 1 error it takes 20µs to correct the error. Blocks wait in
the queue when the decoder falls behind. Suppose that the decoder is initially empty and
that the number of errors in the first 16 blocks are: 0, 1, 4, 1, 0, 4, 0, 1, 0, 3, 1, 2, 1, 2, 1,
4,.
Construct a simulation table for the queuing model, showing arrival times, number of errors,
waiting, service and departure times.
(80 Marks)
(c) From your simulation table in (b), determine the following performance measures (correct
to 2 decimal places for non-integer numbers):
(12 Marks, 2 Marks each)
(i) Average number of blocks in the system
(ii) Average block waiting time
(iii) Maximum simulation time
(iv) Decoder busy duration
(v) Decoder utilization time
(vi) Decoder idle time
QUESTION 2 [40 MARKS]
(a) A small-scale vocational business firm produces two farming implements: hoes and
shovels and realises a net unit profit of N$125 per hoe and N$140 per shovel. Assume
that the firm has up to 250 square metres of iron sheet and 200 metres of wood length
to devote to a small farming project plus a signed contract of supplying 10 hoes and 15
shovels to a family farm during the period of the project. Moreover, assume that it
requires 2 square metres of iron and 0.65 metre of wood to fabricate a hoe and 3 square
metres of iron and 0.85 metre of wood to produce a shovel. Formulate and solve the
model for maximising the firm's profits for hoes and shovels.
(20 Marks)
(b) (i) Define post-optimality analysis for linear optimisation problems
(5 Marks)
(ii) Discuss the analysis for change in the firm's profits on hoes, showing all
expressions to support your conclusion.
(15 Marks)
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