VTU Mechanical Engineering (Semester 7)
Operations Research
December 2014
Total marks: --
Total time: --
INSTRUCTIONS
(1) Assume appropriate data and state your reasons
(2) Marks are given to the right of every question
(3) Draw neat diagrams wherever necessary


1 (a) Define operations research. Explain the phases of operations research.
6 M
1 (b) A firm manufactures two products A and B on which the profit earned per unit are 3 and 4 respectively. Each product is processed on two machines M1 and M2. Product A requires one minute of processing time on MI and two minutes on M2while B requires one minute on M1 and one minute on M2. Machine M1 is available for not more than 7 hrs. 30 mins while machine M2 is available for 10 hrs during any working day. Find the number of units of product A and B to be manufactured to get maximum profit
14 M

2 (a) Solve the following LPP using simplex method
Maximize Z-3x1+2x2
Subjected to constraints
x2+x2≤4
x1-x2≤2
x1, x2≥0
10 M
2 (b) Solve the given problem by using Big-M method.
Maximum Z-- 2x1-x2
Subject to constraints:
3x1+x2-3
4x1+3x2,\ge 6
x1-2x2\le and
x1,x2\ge0
10 M

3 (a) ABC limited has three production shops supplying a product to 5 warehouses. The cost of production varies from shop to shop, cost of transportation from shop to shop, cost of transportation from shop to warehouses also varies. Each shop has a specific production capacity of each warehouse has certain amount of requirement. The cost of transportation are as given below
Shop Warehouse Capacity Cost of production
I II III IV V
A 6 4 4 7 5 100 14
B 5 6 7 4 8 125 16
C 3 4 6 3 4 175 15
Requirement 60 80 85 105 70    

Find the optimum quantity to be supplied from each shop to different warehouse at minimum cost.
12 M
3 (b) A ABC company has 5 takes and 5 Persons to perform. Determine the optimal assignment that minimizes the total cost
Jobs Machines
A B C D E
P 6 7 5 9 4
Q 7 5 10 9 6
R 5 4 3 6 5
S 8 3 5 6 4
T 4 7 5 6 6
8 M

4 (a) Explain the importance of integer programming
5 M
4 (b) Solve the following linear programming by Gomory technique
Maximum Z=x1+x2
Subject to 2x1+x2\le6
4x+5x2\le 20
x2 x2\ge and intergers
15 M

5 (a) Define the following
i) Normal time
ii) Crash time
iii) Free float
6 M
5 (b) R and D activity has 7 activities for which the three time estimate are given below along with its preceding activity
Activity Preceding activity Optimistic time (a) Most likely time(m) Pessimistic time (b)
A - 4 6 8
B A 6 10 12
C A 8 18 24
D B 9 9 9
E C 10 14 18
F A 5 5 5
G D,E,F 8 10 12

i) Draw PERT network
ii) find EST,Lst and slack for each node
iii)Find critical path expected project duration
14 M

6 (a) Briefly explain queuing system and its characteristics
6 M
6 (b) Arrival rate of telephone call at a telephone booth are according to poisson distribution , with an average time of 9 minute between two consecutive arrivals. The length of the telephone call is assumed to be exponentially distributed, with mean 3 minute
i) Determine the probability that a person arriving at the booth will having to wait.
ii) Find the average queue length
iii) The telephone company will install a second booth when convinced that an arrival would expect to have to wait at least four minute for the phone. Find the increase in flow rate of arrival which justify a second booth.
iv) What is the probably that he will have to wait for more than 10 minute before the phone is free?
14 M

7 (a) Explain clearly the following terms
i)Pay off matrix
ii) Saddle point
iii) Fair game
6 M
7 (b) Use dominance to find the optimum strategies for the both player
\[\begin{matrix} B_{1} & B_{2} &B_{3} &B_{4} &B_{5} &B_{6} \end{matrix}\\\begin{matrix} A_{1}\\A_{2} \\A_{3} \\A_{4} \\A_{5} \end{matrix}\begin{bmatrix} 4 &2 &0 &2 &1 &1 \\4 &2 &1 &3 &2 &2 \\4 &3 &7 &-5 &1 &2 \\4 &3 &4 &-1 &2 &2 \\4 &3 &3 &-2 &2 &2 \end{bmatrix}\]
7 M
7 (c) Solve the game by graphical method
\[\begin{matrix} b_{1} &b_{2} \end{matrix}\\\begin{matrix} a_{1}\\a_{2} \\a_{3} \\a_{4} \end{matrix}\begin{bmatrix} 1 &-3 \\3 &5 \\-1 &6 \\4 &1 \end{bmatrix}\]
7 M

8 (a) Define i) Total elapsed time ii) Idle time
4 M
8 (b) List the assumption made while dealing sequencing problem
4 M
8 (c) We have five jobs which must go through the machines A,B and C in the order ABC. Determine a sequence for job taht will minimize the total elapsed time and idle time for each machine.
Job number Processing time in hours
1 2 3 4 5
Machine A 5 7 6 9 5
Machine B 2 1 4 5 3
Machine C 3 7 5 6 7
12 M



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