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Consider the following L.P.P.

Minimize z = 400x + 300y subject to 100x + 200y ≥ 12000, 300x + 400y ≥ 20000, 200x + 100y ≥ 15000 and x, y ≥ 0. Then

Solution

Correct Option: 2

The given constraints are:

100x+200y12000100x + 200y \geq 12000

300x+400y20000300x + 400y \geq 20000

200x+100y15000200x + 100y \geq 15000

x,y0x, y \geq 0


Simplifying the constraints by dividing:

x+2y120x + 2y \geq 120

3x+4y2003x + 4y \geq 200

2x+y1502x + y \geq 150

x,y0x, y \geq 0


All constraints are of "\geq" type, meaning the feasible region consists of points above or to the right of all constraint lines. The region extends infinitely upward and rightward.

Therefore, the feasible region is unbounded.


For minimum value in an unbounded region, the corner points at the intersections of constraint lines need to be examined.

Finding the intersection of x+2y=120x + 2y = 120 and 2x+y=1502x + y = 150:

From 2x+y=1502x + y = 150:

y=1502xy = 150 - 2x

Substituting into x+2y=120x + 2y = 120:

x+2(1502x)=120x + 2(150 - 2x) = 120

x+3004x=120x + 300 - 4x = 120

3x=180-3x = -180

x=60x = 60

Therefore:

y=1502(60)y = 150 - 2(60)

y=150120y = 150 - 120

y=30y = 30

Corner point: (60,30)(60, 30)


Checking at (60,30)(60, 30):

x+2y=60+60=120120x + 2y = 60 + 60 = 120 \geq 120

3x+4y=180+120=3002003x + 4y = 180 + 120 = 300 \geq 200

2x+y=120+30=1501502x + y = 120 + 30 = 150 \geq 150

All constraints are satisfied.


The objective function at (60,30)(60, 30):

z=400x+300yz = 400x + 300y

z=400(60)+300(30)z = 400(60) + 300(30)

z=24000+9000z = 24000 + 9000

z=33000z = 33000

This gives the minimum value as (60,30)(60, 30) is at the corner of the unbounded feasible region.


The feasible region is unbounded and the optimal point is (60,30)(60, 30).

Correct Option: 2

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