lp8- practice problems

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  • 8/18/2019 Lp8- Practice Problems

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    LP-SIMPLEX PRACT ICE PROBLEMS

    Q1) Maximize z = 3x1 + 4x2 + 2x3

    Subject to

    X1 – 2x2 + 4x3 = 0

    Q5)

    Maximize Z=  − + 

    Subject to

    2 +  +3   ≤ 7 

    2  − +4   ≥ 8 

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      , ,   ≥ 0 

    Solve using artificial variables Use both BIG M method and TWO PHASE method.

    Q6). Solve the following LP

    Minimize Z = X1 + 3X2 + X3

    Subject to

    X1 + X3>=30

    X2 + 2X3>=40

    a) Using the Two Phase Method

    b) Also, find the dual of this LP and its solution

    Q7) Maximize f = 200x1 + 400x2 

    ST: t: x1/40 + x2/60 0 

    a) 

    Write the dual to the following problem and verify that (2,0) is a feasible solution to

    the dual

     b)  Use the information in part (a) to obtain the optimal solutions to primal and dual.

    Q9)

    Maximize Z= 8 +4 +9  

    Subject to

    7 +6 +   ≤ 20 

    4 +3 +2   ≤ 29,    ≥0

    Solve dual optimally

    Q10)

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     A factory manufactures three products. Two resources- material and labour are

    required to produce these products as shown below.

    Product Resources(hours) Units

    Profit(Rs.)Material Labour

    1 1 5 9

    2 1 2 73 1 3 5

    There are 80 units f material and 250 hours of manpower available. In order to determine

    the optimal product mix which maximizes the total profit, the following linear program

    was solved.

    Maximize 9 +7 +5  

    Subject to

      + +   ≤ 80 

    5 +2 +3   ≤ 250 

     , ,  >0 

    The optimal solution is shown in the table below.

    4 -3 3 0 0

    Basis                 b

      

    X2

    1

    1

    0

    0

    1/3

    2/3

    -2/3

    5/3

    1/3

    -1/3

    30

    50

     −   0 0 -8/3 -20/6 -4/6 Z=620

    Using sensitivity analysis, answer the following with respect to above table:

    (a) What should be the profit of product 3 before it becomes worthwhile to manufacture?

    Find the most profitable product mix if the profit on product 3 was increased to Rs.8.

    (b) What is the range of profit of Product 1 so that the current solution is still optimum.

    (c)  It is believed that the estimate of the available hours of labour is 250+. find the

    range of values of  for which the given product mix is still optimal.