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OR (Mech) Questions

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Operation Research Techniques

Part-A Questions

1. Define unbounded solution


If value of objective function decreases or increases indefinitely such a solution is
called unbounded solution.

2. What do you mean by a general LPP?


The general LPP calls for optimizing (maximizing / minimizing) a linear function
of variables called the ‘Objective function’ subject to a set of linear equations
and / or inequalities called the ‘Constraints’ or ‘Restrictions’.

3. Define feasible region.


Feasible region is a collection of all feasible solutions (Feasible solution is a
solution for which all constraints are satisfied).

4. Define constraint

5. State any three salient features of a LPP


6. Define infeasible solution
7. Define slack & surplus variable
8. Define optimal solution
9. Write the standard form of LPP in Matrix form.
10. What is degeneracy in LPP?
11. What is key column, key row? How is it selected?
12. Stat the condition for an unbounded solution of a LPP?
13. Define artificial variable.
14. What is the use of artificial variable?
15. Give mathematical formulation of assignment problem.
16. List any three approaches used with transportation problem for determining the
starting solution.
17. What d you mean by transportation problem?
18. What is the use of MODI method?
19. Define degenerate and non-degenerate basic feasible solution of a transportation
problem.
20. What is unbalanced transportation problem? How to solve it?
21. Define an assignment problem.
22. How will you revise the opportunity cost matrix of a n assignment problem, if it does
not give the optimal solution?
23. What do you mean by a project?
24. What do you mean by an activity of a project?
25. Define network.
26. Define EST & LFT.
27. In inventory models, What is mean by q and C3.
28. A Particular item has demand of 9,000 units/year. The cost of one procurement is
Rs.100 and the holding cost per unit is Rs.2.40 per years. The replacement is
instantaneous and no shortages are allowed. Determine the economic lot size.
29. Define Value of the game?
30. When Two-person zero sum game has a saddle point?
31. Differentiate PERT and CPM
32. Define pure strategy.
33. Define group replacement.
34. What is travelling salesman problem?
35. Define assignment problem.
36. What is an unbalanced transportation problem?
Part-B Questions

1. Solve the following LPP problem by simplex method


Maximize 15 x1  6 x 2  9 x3  2 x 4
Subject to
2 x1  x 2  5 x3  6 x 4  20
3 x1  x 2  3 x3  25 x 4  24
7 x1  x 4  70
x1 , x 2 , x3 , x 4  0

2. Solve the following L.P.P by the graphical method.


Maximize z  3 x1  2 x 2
Subject to  2 x1  x 2  1
x1  2
x1  x 2  3, and x1 , x 2  0

3. Solve the following LPP by Big-M method


Minimize Z  3x  2y
subject to 7x  2y  30
5x  4y  20
2x  8y  16 x, y  0

4. Determine basic feasible solution to the following


transportation problem using North West Corner Rule
SinK
A B C D E Supply
P 2 11 10 3 7 4
Origin Q 1 4 7 2 1 8
R 3 9 4 8 12 9
Demand 3 3 4 5 6

5. Find the starting solution of the following transporation


model by Least Cost method
1 2 3 4 Supply
I 21 16 25 13 11
II 17 18 14 23 13
6. Find an optimal solution by
III 27 18 41 41 19
MODI method of the following
Demand 10 12 15 15
matrix using VAM for finding the
initial solution

7. A machine operator has to perform two operations, turning and threading on a


number of different jobs. The time required to perform these operations (in minutes) for
each job is known. Determine the order in which the jobs should be processed in order
to minimize the total time required to turn out all the jobs.
Time for turning Time for threading
Job
(minutes) (minutes)
1 3 8
2 12 10
3 5 9
4 2 6
5 9 3
6 11 1

7. Draw the network and determine the critical path for given data

Jobs 1-2 1-3 2-4 3-4 3-5 4-5 4-6 5-6

Duration 6 5 10 3 4 6 2 9

8. Construct the 1 2 6 7 network for the project whose activities


are given below and compute the total, free and
0 4 2 12
independent float of each avtivity and hence determine
the critical path 3 1 5 11 and project duration.
10 10 10
Activity 0-1 1-2 1-3 2-4 2-5 3-4 3-6 4-7 5-7 6-7
Duration 3 8 12 6 3 3 8 5 3 8
(in weeks)
9. A particular item has a demand of 9,000 units/year. The cost of one procurement
is Rs.100 and the holding cost per unit is Rs.2.40 per year. The replacement is
isntantaneous and no shortages are allowed. Determine
i) the economic lot size.
ii) the number of orders per year
iii) the between orders
iv) the total cost per year if the cost of one units is Re.1

10. An item is produced at the rate of 50 items per day. The demand occurs at the
rate of 25 items pr day. If the setup cost is Rs.100 per setup and holding cost is
Re.0.01 per unit of item per day, find the economic lot size for one run, minimum
total cost for one run.

11. Using the principle of Dominance solve the following game


 8 10 9 14
10 11 8 12
 
13 12 14 13

12. Solve the following game by graphical method


 6 4 1 2 7 
 7 5 2 5  6

13. Reduce the game by dominance and find the game value

I II III IV
I 3 2 4 0
II 3 4 2 4
III 4 2 4 0
IV 0 4 0 8

14. Solve the transportation problem using VAM and find the
optimal solution whose cost, demand, supply are given by the
following table

W1 W2 W3 W4 W5 Supply

P1 20 28 32 55 70 50
P2 48 36 40 44 25 100

P3 35 55 22 45 48 150

Demand 100 70 50 40 40

15. An item is produced at the rate of 50 units per day. The demand is at the rate of
25 units per day. The set up cost is 100 per unit per day. Find the EOQ and the
minimum annual inventory cost. After how many days should production be
stopped during each run?

16. A manufacturer has a supply 12000 units of a product per year to his customer.
Shortages are not permitted and there is no lead time. The inventory holding cost is
Rs.0.20 per unit per month and the set up cost per run is Rs.350. Determine the
economic lot size, the period of one run, the minimum annual inventory cost.

17. In a game of matching coins with two players, suppose A wins one unit value when
there are two heads, wins nothing there are two tails, and losses ½ units value when
there are one head and one tail. Determine the payoff matrix, the best strategy for
each palyer,and the value of the game.

18. Use simplex method to


Min Z=x2-3x3+2x5
3 x 2  x3  2 x 5  7
 2 x 2  4 x3  12
 4 x 2  3x3  8 x5  10
Subject to and x 2 , x3 , x5  0
19. Solve the following game by graphical method
 6 7 
 4  5 

1  2
 
 2 5 
 7  6 

 3 1 1 2
 2 3 2 3
20. Solve the following game 
 2 2  1 1 
21. Find the sequence for the following eight jobs that will minimize the total
elapsed time for the completion of all the jobs. Each job is processed in the same
order “C, A, B”. Entries give the time in hours on machines

Jobs 1 2 3 4 5 6 7 8
Times on Machine A 4 6 7 4 5 3 6 2
Times on Machine B 8 10 7 8 11 8 9 13
Times on Machine C 5 6 2 3 4 9 15 11

22. A project consists of the tasks A, B, C,D,E ,F,G, H, I with the following data

Activity A B C D E F G H I

Preceding -- -- -- A A B,D C B F,G


activity

Duration 23 8 20 16 24 18 19 4 10

Construct network. Find critical path. Also find Total, Independent and Free
floats

23. Solve the following traveling salesman problem. A salesman is planning to tour cities
B,C, D,E starting from his home city A.
The inter-city distances are shown in the following table

City A B C D E

A -- 103 188 136 38

B 103 -- 262 176 52

C 188 262 -- 85 275

D 136 176 85 -- 162

E 38 52 275 162 --

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