BIT 4th Semester
Operations Research Question Paper 2080

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ORS 255-2080 ✡
Tribhuvan University
Institute of Science and Technology
2080
Bachelor Level/Second Year/Fourth Semester/Science
Bachelors in Information Technology (ORS 255)
(Operations Research)
Full Marks:60 Pass Marks:24 Time:3 hours

Candidates are required to give their answers in their own words as for as practicable.
The figures in the margin indicate full marks

Section A
Long Answer Questions
Attempt any Two question.
[2x10=20]
1.

Solve the given linear programming problem (LPP) by using simplex method and interpret the findings.
Maximize Z = 4A + 3B + 6C
Subject to the constraints:
2A + 3B + 2C≤ 440
4A + 3C≤ 470
2A + 5B≤ 430,
and A, B, C≥ 0

2.

A project consists of nine activities whose time estimates (in weeks) and other characteristics are given below:

ActivitiesABCDEFGHI
Preceding activities---AAB, DB, DC, FE
Optimistic time2662118394
Most likely time46125141061510
Pessimistic time66248231292716

(a) Show the PERT network diagram for the project.
(b) Identify the critical activities.
(c) What is the expected project completing time and its variance?

3.

A milk salesman estimates the probability of the demand for a litre of milk is as follows:

Demand1112131415
Probability0.100.150.300.250.20

He purchases a litre of milk @ of Rs. 60 and sells it @ of Rs. 70. Assuming that unsold milk has no scrap value, find
(a) Find optimum quantity that would obtain Max. EMV.
(b) Find the minimum value of EOL.
(c) What is the value of expected profit with perfect information (EPPI)?

Section B

Attempt any Eight questions

[8x5=40]
4.

The ABC company has three jobs to be done on three machines. Each job must be done on one and only one machine. The cost of each job on each machine is given in the following table.

Machine
JobsXYZ
A468
B234
C485

By using Hungarian method, find the job assignments which will minimize the cost.

5.

Food X contains 6 units of vitamin A and 7 units of vitamin B and costs Rs. 5 per gram. Food Y contains 8 units of vitamin A and 12 units of vitamin B and costs Rs. 18 per gram. The daily minimum requirement of vitamins A and B are respectively 100 units and 138 units respectively. Formulate the problem as a LPP with the objective function minimizing the cost.

6.

Customers arrive at a bank having single counter at the rate of 25 customers per hour. Time required to serve a customer has exponential distribution and average number of customer served per hour is 30. Find the average number of customers in queue and in system as well.

7.

Find the initial solution by using Vogel's Approximation Method (VAM).

FromToPQRSSupply
A193050107
B703040609
C408702018
Demand5871434

8.

The following is the payoff matrix of a game being played by A and B. Determine the optimal strategies for the players and the value of the game.

A's strategiesB's strategies
B₁B₂B₃
A₁120- 80- 20
A₂607030
A₃-1007020

9.

Draw the network diagram and identify critical path and bottleneck activities.

ActivityABCDEFG
Predecessors-AAAB,CC,DE,F
Time ( in days)7456756

10.

Describe dominance rule method for solving a problem of game theory.

11.

Describe different types of queuing disciplines used in serving a customer in a queue.

12.

Write short notes on:
(a) Marginal analysis approach in decision making.
(b) Modified distribution (MODI) method.