TYBMS Semester 6 Operation Research Q.P. November 2019 with Solution

 Paper/ Subject Code 86001/ Operation Research

TYBMS Semester 6 Operation Research 

(Q.P. 2019 with Solution)

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1) April 2019 Q.P. with Solution (PDF) 

2) November 2019 Q.P. with Solution (PDF)

4) April 2023 Q.P. with Solution (PDF)

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Note:

1. All questions are compulsory. (Subject to Internal Choice)

2. Figures to the right indicate full marks

3. Use of non-programmable calculator is allowed and mobile phones are not allowed.

4. Normal distribution table is printed on the last page for reference. Support your answers with diagrams / illustrations, wherever necessary

6. Graph papers will be supplied on request.

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Q.1A) Match the right and closely related answer from Column Y with the text / term given in Column X. ( Attempt Any 7 questions )


Column X

Column Y

1) Value of Game = 0

a) Training programme scheduling

2) Optimistic Time

b) If no. of Row > No. of Columns

3) Application of O.R. in HRM

c) Minimization types transportation problem

4) Pessimistic Time

d) Does not affect the feasible solution

5) Add Dummy Row in Assignment

e) To maximize per capita income

6) Redundant Constraint in Graphical

f) one player’s gain is the other player’s Loss

7) Application of O.R. in Finance

g) If no. of Row < No. of Columns

8) Transportation elements as time

h) fair game

9) Add Dummy Column in Assignement

i) Shortest and ideal Time estimate in PERT

10) Zero Sum Game

j) Time estimate in PERT by considering worst delays

ANS :

Column X

Column Y

1) Value of Game = 0

f) one player’s gain is the other player’s Loss

2) Optimistic Time

i) Shortest and ideal Time estimate in PERT

3) Application of O.R. in HRM

a) Training programme scheduling

4) Pessimistic Time

j) Time estimate in PERT by considering worst delays

5) Add Dummy Row in Assignment

g) If no. of Row < No. of Columns

6) Redundant Constraint in Graphical

d) Does not affect the feasible solution

7) Application of O.R. in Finance

e) To maximize per capita income

8) Transportation elements as time

c) Minimization types transportation problem

9) Add Dummy Column in Assignement

b) If no. of Row > No. of Columns

10) Zero Sum Game

h) fair game

Q.1 B) State whether following statements True or False: (Attempt any 8)                             (8)

1) One of the areas of application of Operations Research is in Agriculture.

Ans: False

2) A linear programming model consists of only decision variables and constraints

Ans: True

3) In graphical method of LPP the optimum value occurs anywhere in feasible region.

Ans: True

4) If the assignment elements are cost elements then the objective of the optimal assignment is to maximize the cost.

Ans; False

5) In transportation problem, number of basic allocated (or Occupied) cells should be exactly m+n+1, so that it becomes non-degenerate.

Ans; False

6) Dummy activity does not consume time or resources.

Ans: True

7) The three time estimates employed in PERT are: optimistic time, average expected time, and pessimistic time.

Ans: True

8) In Sequencing the time taken by each job in changing over from one machine to another is negligible.

Ans: False

9) The row [-1,10, 20] dominates the row [0,0,0]

Ans: False

10) The column [0,-1,-2] dominates the column [0,-1, -1]

Ans: False

 Q2 A) Use Graphical method to solve the following Linear programming problem                              (8)

Objective Function

Max Z = 3X1 + 4X2

Subject to Constraints

3X1 + 2X2 18

X1 5

X2 6

X1 ,X2 0

Ans:

Click here to Video Solution

3X1 + 2X2 ≤ 18 ---- (i)

3X1 + 2X2 = 18

Let X1 = 0

3(0) + 2 X2  = 18

2 X2 = 18              Therefore X2 = 9                       (X1, X2) = (0, 9)

Let X2 = 0

3 X1 + 2(0)  = 18

3X1 = 18               Therefore X1 = 6                       (X1, X2) = (6, 0)

X1 ≤ 5 ---- (ii)

Therefore X1 = 5                       (X1, X2) = (5, 0)

X2 ≤ 6 ---- (iii)

Therefore X2 = 6                       (X1, X2) = (0, 6)


Vertex Corner Points :

Vertex

Coordinate Points

Max Z = 3X1 + 4X2

O (0,0)

X1 = 0,  X2 = 0

3(0) + 4(0) = 0

A (0,6)

X1 = 0,  X2 = 6

3(0) + 4(6) = 24

B (2.5,6)

X1 = 2.5,  X2 = 6

3(2.5) + 4(6) = 31.5

C (5,2.5)

X1 = 5,  X2 = 2.5

3(5) + 4(2.5) = 25

D (5,0)

X1 = 5,  X2 = 0

3(5) + 4(0) = 15

Therefore Max Z = 31.5

where, X1 = 2.5,  X2 = 6

Q2.B) There are 7 different products in a machine shop. Their manufacturing time in Hrs on machines 1 and 2 are given below. Each of the product must go through two machines and 2 in the order 1-2.

Products

Time in HRs on Machine 1

Time in HRs on Machine 2

A

20

10

B

30

25

C

10

25

D

20

30

E

55

35

F

60

40

G

50

45

 

i) Find the sequence of Products that minimizes the total elapsed time.

(ii) Find the Total Elapsed Time for the optimum Sequence.

(iii) Calculate the idle time for machine 1.

(iv) Calculate the idle time for machine 2.

Ans: i) The sequence of Products that minimizes the total elapsed time

Machine 1                                                                                          Machine 2

C

D

G

F

E

B

A

 ii) Calculating Elapse Time:

Products

Machine 1

Machine 2

In

Out

In

Out

C

0

0 + 10 = 10

10

10 + 25 = 35

D

10

10 + 20 = 30

35

35 + 30 = 65

G

30

30 + 50 = 80

80

80 + 45 = 125

F

80

80 + 60 = 140

140

140+ 40 = 180

E

140

140 + 55 = 195

195

195 + 35 = 230

B

195

195 + 30 = 225

230

230+ 25 = 255

A

225

225 + 20 = 245*

255

255 + 10 = 265*

 

Therefore, Total Elapse Time for Machine = 265 Hrs

iii) Idle Time for Machine :

Machine 1 = 265 – 245 = 20 Hrs

Machine 2 = 265 – 210 = 55 Hrs

OR

Q.2 C) 'BMS Ltd' prepared a set of interdependent activities for their upcoming project; details of which is given in below table

Activity

Preceding Activity

Duration (weeks)

(1,2) A

-

2

(1,3) B

-

3

(2,4) C

A

3

(3,5) D

B

4

(4,6) E

C

3

(5,6) F

C, D

2

(6,7) G

E. F

9

(4,5) Dummy

C

0

(i) Construct a network diagram, find critical path and project completion time.        (3)

(ii) Tabulate Calculate Earliest Start and Finish Time, Latest Start and Finish Time and Total Float.                                                                                                                             (5)

Ans: Critical path :

A-C-G-E = 2 + 3+ 3+ 9 = 17 weeks

A-C-X-F-G = 2+3+0+ 2 + 9 = 16 weeks

B-D-F-G = 3 +4 + 2 + 9 = 18 weeks

Therefore, Critical path: B-D-F-G

Project Completion = 18 weeks



Activity

EST = Ei

EFT = Ei + t

LST = Lj + t

LFT = Lj

(1,2) A

0

0 + 2 = 2

3 – 2 =1

3

(1,3) B

0

0 + 3 = 3

3 – 3 = 0

3

(2,4) C

2

2 + 3 = 5

6 – 3 = 3

6

(3,5) D

3

3 + 4 = 7

7 – 4 = 3

7

(4,6) E

5

5 + 3 = 8

9 – 3 = 6

9

(5,6) F

7

7 + 2 = 9

9 – 2 = 7

9

(6,7) G

9

9 + 9 = 18

18 – 9 = 9

18

(4,5) Dummy

5

5 + 0 = 5

7 – 0 = 7

7

Q.2 D) A company is transporting its units from three manufacturing plants P1, P2 and P3 to four distribution centres D1, D2, D3 and D4. The supply and demand of units with unit cost of transportation (in Rs.) and the schedule followed from plants to distribution centres are given below: (The numbers which are in circle indicates number of units transported from plant to distribution centre).


(i) Test the solution for optimality                                                            (3)



(ii) If solution is not optimal find optimal solution.                                  (4)



Q.3 A) Following payoff matrix refers to a two-player game, player and player B. Each player has four strategic options.

 


(i) Find the Maximin Strategy.                                                 (3)

(ii) Find the Minimax Strategy.                                                (3)

(iii) What is the value of the Game?                                         (1)



Q.3 B) There are five jobs (namely 1,2,3,4 and 5), each of which must go through machines A, B and C in the order ABC. Processing Time (in hours) are given below:

Jobs

1

2

3

4

5

Machine A

5

6

6

9

6

Machine B

3

2

5

5

3

Machine C

3

7

5

6

7

 

(i)Find the sequence that minimizes the total elapsed time required to complete the jobs.              (2)

(ii) Calculate the total elapsed time                                                          (3)

(iii) Idle time on Machine A, Machine B and Machine C.                   (3)

Ans: i) The sequence of Products that minimizes the total elapsed time

Converting the 3-machines problem into a fictitious 2-machines problem where G and H are the two fictitious Machines.

G = A + B

H = B + C

Jobs

1

2

3

4

5

Machine G

8

8

11

14

9

Machine H

6

9

10

11

10

 

Machine G                                                            Machine H

2

5

4

3

1

 ii) Calculating Elapse Time:

Jobs

Machine A

Machine B

Machine C

In

Out

In

Out

In

Out

2

0

0 + 6 = 6

6

6 + 2 = 8

8

 8 + 7 = 15

5

6

6 + 6 = 12

12

12 + 3 = 15

15

15 + 7 = 22

4

12

12 + 9 = 21

21

21 + 5 = 26

26

26 + 6 = 32

3

21

21 + 6 = 27

27

27 + 5 = 32

32

32 + 5 = 37

1

27

27 + 5 = 32*

32

32 + 3 = 35*

37

37 + 3 = 40

 Therefore, Total Elapse Time for Machine = 40 Hrs

iii) Idle Time for Machine :

Machine A = 40 – 32 = 8 Hrs

Machine B = 40 – 18 = 22 Hrs

Machine C = 40 – 28 = 12 Hrs 

OR

Q.3 C) Five salesmen are to be assigned to five territories. Base on past performance, the following table shows the annual sales (is Rs. lakh) that can be generated by each salesman in each territory. Find optimum assignment to maximise sales.

Salesmen

Territory

T1

T2

T3

T4

T5

S1

24

12

8

10

7

S2

29

25

28

12

14

S3

13

16

14

23

28

S4

15

10

19

28

23

S5

18

17

23

14

8

 Ans: 

1)    Regret Matrix :

Salesmen

Territory

T1

T2

T3

T4

T5

S1

5

17

21

19

22

S2

0

4

1

17

15

S3

16

13

15

6

1

S4

14

19

10

1

6

S5

11

12

6

15

21

2)    Row Minimization

Salesmen

Territory

T1

T2

T3

T4

T5

S1

0

12

16

14

17

S2

0

4

1

17

15

S3

15

12

14

5

0

S4

13

18

9

0

5

S5

5

6

0

9

15

3)    Column Minimization / Analysis:

Salesmen

Territory

T1

T2

T3

T4

T5

S1

0

8

16

14

17

S2

0

0

1

17

15

S3

15

8

14

5

0

S4

13

14

9

0

5

S5

5

2

0

9

15

3) Allocation:

Salesmen

Territory

T1

T2

T3

T4

T5

S1

0

8

16

14

17

S2

0

0

1

17

15

S3

15

8

14

5

0

S4

13

14

9

0

5

S5

5

2

0

9

15

4)    Calculating Total Sales:

Salesmen

Territories

Sales

S1

T1

24

S2

T2

25

S3

T5

28

S4

T3

28

S5

T3

23

 

Total

128

 Therefore, Maximization of Sales = 128 Lakhs

Q.3 D) Use Simplex method to solve the following Linear programming problem                 (8)

Maximize Z=4x1+7x2

Subject to the constraints.

x1+3x2 ≤ 18

4x1 +2X2 ≤ 8

X1 , X2 0

 Ans: Standard Form:

Maximize Z= 4x1+7x2 + 0S1 + 0 S2

Subject to the constraints.

x1+3x2 + 1S1 + 0 S2 ≤ 18

4x1 +2X2 + 0S1 + 1S2 ≤ 8

X1 , X2, S1, S2 ≥ 0



New Value of Key Row = Old Value / Key Element

                                      =        8        4        2        0        1

                                                          4

Corresponding Key Row

= Old Value – {Corresponding Value of Key Column – New Value of Key Row}

b = 18 – (1 x 2) = 16

X1 = 1 – (1 x 1) = 0

X2 = 3 – (1 – 1/2) = 5/2

S1 = 1 – (1 X 0) = 1

S2 = 0 – (1 X 1/4) = -1/4

 


∆ is Zero and Negative value.

It is optimal solution.

Maximize Z=4x1+7x2

Where, X1 = 18 and X2 = 0

Maximize Z= 4(18)+7(0) = 72

Maximize Z= 72 

Q.4 A) The table given below has been taken from the solution procedure of a transportation problem, involving minimization of cost (in Rs.)

i) Show that the above solution is optimal. Find an optimal solution.                         (3)

ii) Does the problem have multiple optimal solutions? Give reasons.                         (2)

iii) If multiple solutions exist, then find one more optimal solution.                            (3)

iv) Comment upon the managerial significance of multiple optimal solutions         (2)


Allocation Cell : Cost = ui + vj {+, + = -} {+, - = +}
Cost = ui + vj
30 = 0 + vj
vj = 30

Non-Allocation cell = Cost - ui + vj

Where Non-Allocation Cell is Zero (0),
Therefore, It is optimal Solution.



Hence It is optimal value
Total Cost = (8 X 75) + (18 X 44) + (18 X 44) + (12 X 30) + (16 X 47)  
                = 600 + 792 + 792 + 360 + 752    = Rs. 3296
 
iv) managerial Significance of multiple optimal Solution is flexibility in decision making available to the management.

Since two optimal solution with Same minimum cost- are available must choose any one optimal Solution as per their convenience to the management- management

Q.4 B) A company is making a chart to decide the minimum amount of constituents like proteins, vitamins, carbohydrates, fats etc. Which a man needs on daily basis to fulfil his requirement for medical awareness. The choice is to be made from different type of foods (4 types). The yields per unit for different types of foods are explained below in the chart. Formulate the given linear programming problem.                                                                                                                                     (5)

Types of food

Yield per Unit

Cost per unit

 

Proteins

Fats

Vitamins

(Rs.)

A

5

6

12

130

B

7

6

9

125

C

16

20

14

160

D

12

18

10

120

Minimum Req.

1600

800

100

 

Ans:

Formulate LPP

Let X1 = No. of unit of A

X2 = No. of unit of B

X3 = No. of Unit of C

X4 = No. of Unit of D

Z = Total Cost

Min Z = 130 X1 + 125 X2 + 160 X3 + 120 X4

Subject Constraints,

5 X1 + 7 X2 + 16 X3 + 12 X4 ≥ 1600  ------ (Proteins)

6 X1 + 6 X2 + 20 X3 + 18 X4 ≥ 800  ------ (Fats)

12 X1 + 9 X2 + 14 X3 + 10 X4 ≥ 1000  ------ (Proteins)

X1, X2, X3, X4 ≥ 0 

4) (C) A Project which is planned using PERT technique has following details of Average Expected Times calculated using the formula, te=(a+4m+b)/6 and the details of standard deviation

Activity

Average Expected Time in weeks (te)

S.D

1-2

2

1

1-3

5

0.5

2-3

4

0.5

2-4

8

1

3-5

3

1

4-6

5

0.5

5-6

2

1

6-7

3

1

 a) i) Construct the network diagram of PERT network and find expected completion time of the project. (3)

ii) Calculate and tabulate the Variance of activity.                                                              (2)

b) iii) Determine the probability of completing the project in 17 Weeks.                  (2)

iv) If there is a huge penalty for exceeding the project completion deadline of two weeks after estimated projected completion time (Tor Critical Path Duration). What is the probability of being penalized? (2)

v) Find project completion time for 95% confidence level.                                             (2)

vi) If the fixed cost of the project is Rs. 4000000/- and the variable cost is Rs. 20000/- per week. Find the amount the firm should bid under the policy of 95% confidence of completion of the project. (For the purpose of bidding, consider only cost that is break even no loss and no profit)              (2)

vii) If the project manager wants to complete the project with 95% confidence in 19 weeks, by how much time he crash the critical activities?                                                                          (1)

viii) If the head of activity 3-5 wants to work overtime so that he can complete this activity in 2 weeks (instead of 3 weeks), should he be permitted?                                                                              (1)

Ans: 

Activity

Average Expected Time in weeks (te)

S.D

Variance S.D2

1-2

2

1

1

1-3

5

0.5

0.25

2-3

4

0.5

0.25

2-4

8

1

1

3-5

3

1

1

4-6

5

0.5

0.25

5-6

2

1

1

6-7

3

1

1

 

  


 Critical Path:

1-2-4-6-7 = 2+8+5+3 = 18 weeks

1-2-3-5-6-7 = 2 + 4 + 3 + 2 + 3 = 14 Weeks

1-3-5-6-7 = 5+3+2+3 = 10 Weeks

Therefore, Critical Path = 1-2-4-6-7

Project Completion = 18 weeks

ii) Variance of Critical Path = 1 + 1 + 0.25 + 1 = 3.25

S.D. = √3.25                   = 1.8027

B) i) Time = 17 Weeks

          Te = 17 weeks

Z = t – C.P. / S.D.          

Z =  17 – 18 / 1.80

Z = -1 / 1.80 = - 0.56

Table Value = - 0.2123

P (17 weeks) = 0.5 – 0.2123

= 0.2877

= 28.77 %

iv) Project Completion = 18 + 2 = 20 Weeks

Penalty will impose when project completion 20 Weeks.

P (Non-Completion) = 1-p (20 Weeks)

Z = 20-18 / 1.80    = 2/ 1.80     = 1.11

Table Value = 0.3643

P(20 Weeks) = 0.5 + 0.3643 = 0.8643

P (Non-Completion) = 1- 0.8643

Penalty = 0.1357

Project completion time for 95% Confidence level 

Confidence level = 95%

p = 0.95

Table value = 0.95 -0.5 = 0.45 (0.4505)

Corresponding Z = 1.65

Z = t - CP / S.D.    

1.65  =  t - 18 / 1.80

1.65 X 1.80 = t - 18

2.97 = t - 18

2.97 + 18 = t

t = 20.97 Appx 21 weeks

vi) If the fixed cost of the project is Rs. 4000000/- and the variable cost is Rs. 20000/- per week.

Total Cost = Fixed Cost + Variable Cost

                    = 40,00,000 + 20,000 (21)    = 40,00,000 + 420,000    = 44,20,000

Project Manager should biding on Rs. 44,20,000 where he will get break even point.

vii) Since the corresponding project duration 95% confidence is 21 weeks, but the project manager wants to complete in 19 weeks.

Hence, Required Crashing = 21 -19 = 2 weeks

Viii) No, Project Manager should not allow to overtime the head activities 3-5.

Q.5 A) Define Operations Research. Discuss the advantages and limitations of O.R. (7)

Ans:

Definition of Operations Research:

One of the classical definitions of OR is - "Operations Research is the application of scientific methods, techniques and tools to problems involving the operations of systems so as to provide those in control of operations with optimum solutions to the problems."

LIMITATIONS OF OPERATIONS RESEARCH TECHNIQUES:

Some of the major limitations of OR techniques are: (1) In construction of mathematical models, sometimes assumptions are necessary to simplify model construction. But over- simplification of a model or too many assumptions can make the model unrealistic.

(2) OR techniques are quantitative in nature. Hence, these techniques do not consider qualitative or intangible factors such as customer perceptions, employee motivation levels, quality of executives, advantage of experience etc.

(3) All business situations cannot be responded with quantitative techniques. Some business situations require gut feeling, initiative or managerial judgement. OR techniques cannot be applied in such situations.

B) What do you mean by alternative optimal solution in an Assignment? How do you identify alternative solution in an Assignment problem? Further what is the procedure to find that alternative solution? (8)

Ans:

Alternate or Multiple Optimal Solutions:

An assignment problem can have more than one possible combination of Assignments it is a case of Alternate optimal solutions. But all possible combinations have the same final (optimal) answer.

An Assignment problem may have more than one optimal solution, which is called multiple optimal solutions. The meaning of multiple optimal solutions is - The total cost or total profit will remain same for different sets or combinations of allocations. It means we have the flexibility of assigning different allocations while still maintaining Minimum (Optimal) cost or Maximum (Optimal) profit.

We can detect multiple optimal solutions when there are multiple zeroes in any column or row in the final (Optimal) table in the Assignment problem. It means we have an option of allocating different assignments to a particular job or worker.

When the matrix fails the test for presence of optimal solution, we need to perform "iteration" to improve the solution (i.e. to remove degeneracy). In "iteration", we perform following operations for writing the next table:

[A] Find minimum uncovered value in the present matrix.

[B] Subtract it from all uncovered values in the matrix.

[C] Add it to all double covered values (i.e. intersection values) in the matrix.

[D] All other values in the matrix remain same.

OR

C) Answer Any 3 of the following:                                                                                            (15)

i) Assumptions in LPP

Ans: Assumptions in LP:

(1) Available quantities of resources and consumption per unit from resources is known exactly and with certainty.

(2) Production of finished products is possible in any fractions, so is consumption of resources.

(3) All external factors are constant.

(4) The problem involves only one major objective.

ii) Degeneracy in Transportation

Ans: DEGENERACY IN TRANSPORTATION:

Degeneracy occurs when in a Transportation table, number of allocations are less than [number of rows + number of columns - 1].

It means the rim condition is not satisfied.

Rim Condition:

Number of allocations should be equal to [m + n - 1] . Where,

m = Number of Rows.

n = Number of Columns.

If a transportation solution is degenerate, i.e., having degeneracy then we cannot calculate values of u and v'.

Hence, the solution cannot be tested for optimally (A cannot be calculated).

To remove degeneracy, we add an imaginary entry called Epsilon (e) in the solution.

Epsilon is a zero value allocation Its only purpose is to facilitate calculation of 'u and v'

Where to place Epsilon (e): Epsilon is placed in an independent position i.e., a position where it does not form a closed loop with other allocations.

This kind of looping between the allocations and Epsilon should not take place.

iii) Principles of Dominance

Ans: Principles of Dominance are used for reducing the game matrix of a two person zero-sum game, if the game matrix contains large number of strategies.

Principles:

(1) Rules for Rows: If All the elements in a Row are less than or equal to the corresponding elements in another Row, then this Row is said to be dominated by the another Row and can be eliminated from the game matrix to reduce the order of the matrix.

(2) Rules for Columns: If All the elements in a Column are greater than or equal to the corresponding elements in another Column, then this Column is said to be dominated by the another Column and can be eliminated from the game matrix to reduce the order of the matrix.

iv) Assumptions in Job Sequencing

Ans: PRINCIPAL ASSUMPTIONS:

(1) Each machine can perform only one type of operation and can undertake only one job at a time.

(2) Only one machine of each type is available. 

(3) All jobs require the same sequence of operations.

(a) In a two machines problem, each job is processed first on machine A and then on machine B.

(b) In a three machine problem, the sequence of operations is A, B,C.

(4) The processing times of all jobs on all machines are known and remain constant.

(5) Each job must be completed before another job is taken up for processing.

(6) No job is required more urgently than the other. 

(7) Transit time to move a job from one machine to another is negligible.

v) Dummy activity and its use in network analysis

Ans: DUMMY ACTIVITY:

A Dummy activity does not consume any time or resources. It is represented by a dotted line. The purpose of Dummy activity is to represent logical relationship of dependency.

Dummy activity is required in following cases: (a) Two activities are performed concurrently and a third activity depends on both of these activities. 

(b) Two concurrent activities which need to be connected to correctly represent the precedence relationship of succeeding activities. 






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