UGC NET CSE | November 2017 | Part 3 | Question: 69

Question

Consider the following LPP:

Min $Z=2x_1+x_2+3x_3$

Subject to:

$x_1 – 2x_2+x_3 \geq 4$

$2x_1+x_2+x_3 \leq 8$

$x_1-x_3 \geq 0$

$x_1, x_2, x_3 \geq 0$

The solution of this LPP using Dual Simplex Method is

• A. $x_1=0, x_2=0, x_3=3$ and $Z=9$
• B. $x_1=0, x_2=6, x_3=0$ and $Z=6$
• C. $x_1=4, x_2=0, x_3=0$ and $Z=8$
• D. $x_1=2, x_2=0, x_3=2$ and $Z=10$

Comments

https://gateoverflow.in/196397/ugc-net-nov-2017-paper-q-69

Answer 1

Ans. is C : x1=4, x2=0, x3=0 and Z=8

Comments

How to solve such a big LPP in 2 min ?

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If answer required in two minutes for LPP

Hit and trail method

Put the given values in option in the equations of the question and check whether which option satifies the equations, amongst them only one will qualify the criteria.

 

x1-2x2+x3>=4

Put the values of option c and d here in this equation.

You will find it satisfies , similarly put the values in other equations.

Here in this question option c and d both satisfies but then check the objective function which is minimization so option c satisfies.

 

This rule can be applied to other LPP problem of same type.